LOW←TECH MAGAZINE English

Communal Luxury: The Public Bathhouse

Tue, 17 Sep 2024 00:00:00 +0000

Image: Bathhouse built on top of a hot pool, Taiwan. Photo from early 20th century, public domain.

No Running Water at Home

For people in industrial societies, few activities demand more privacy than washing and grooming the body. We usually do it alone, in our private bathrooms, with locked doors. Seen in a historical context, that is unusual. Bathing in the presence of others has been the rule rather than the exception. As late as the first half of the twentieth century, many households, even in the most advanced industrial societies, did not have running water at home, let alone a private bathroom. ¹

A bathroom requires a domestic water supply, but also a sewer drain, and an energy source to heat the water. Of course, it’s possible to have a hot bath at home without these infrastructures. Ever since Antiquity, the rich have built private baths in their houses. Most often, they could do that because less well-off people - either servants or slaves - filled and emptied their bathtubs with bucketloads of water and collected firewood to heat them.

However, for most people, it was more practical to take their bodies to the water rather than the other way around. For some, that meant bathing in rivers, lakes, and springs. For others, especially in urban environments, it meant visiting the public bathhouse.

Image: Bathhouse in Aachen Germany, by Jan Luyken, 1682.

Is Bathing Unsustainable?

Modern bathing practices are a textbook example of an unsustainable lifestyle based on fossil fuels. Hot water production is the second largest energy use in many homes (after space heating and/or cooling), and much of it is used for bathing or showering. ² The modern bathroom also uses a lot of water and adds extra energy use through space heating and waste-water treatment. Building and renovating bathrooms requires resources, too.

Sustainability advocates follow two strategies to address these problems. The first strategy concentrates on technological solutions, such as low-flow showerheads, water boilers heated by solar collectors, waste-water heat recovery systems, and greywater recycling. The second strategy counts on behavioral or social changes by questioning modern standards of cleanliness and comfort: bathing or showering shorter and less frequently, taking cold showers, or doing a cat wash at the sink. ²³

These strategies are unlikely to bring much results. Many technological fixes are difficult or impossible to install in existing buildings, especially in cities. For example, as the number of floors increases, an apartment building quickly runs out of roof space to install solar collectors for all residents. On the other hand, promoting discomfort as a sacrifice for sustainability is unlikely to engage broader environmental practices. ³⁴

Communal bathing makes it easier to disconnect bathing practices from fossil fuels.

Communal bathing could be a third approach, but it’s rarely mentioned. That’s remarkable because, in terms of resource efficiency, it’s hard to beat. Building and operating a bathhouse for 1,000 people requires much less energy than building and operating 1,000 individual bathrooms. A public bathhouse is also more efficient concerning materials, money, and space. ⁵

Just as importantly, public bathing makes applying the sustainable technologies mentioned above more feasible. That further reduces energy consumption and makes it possible to disconnect bathing practices from fossil fuels. Finally, a public bathhouse can achieve significantly improved sustainability without promoting discomfort. On the contrary, pooling resources to build something for a community rather than for every household separately allows for a high level of sustainable extravagance. That may be an easier sell than cold showers.

Image: Public bathhouse in Dunkirk, France, opened in 1897.

Bathing in Rivers, Lakes, and Hot Springs

Nature has provided humans with bathing facilities through streams, rivers, pools, lakes, waterfalls, and rain showers. Humanity spent much time in tropical Africa, where bathing did not require artificially heated water for comfort. When we moved into colder climates, Nature presented us with another solution: hot springs. Many tens of thousands of thermal springs exist around the planet — only a few present-day countries lack them entirely. ⁶⁷

Bathing in hot springs was common in ancient civilizations all over the world. However, it’s a practice that goes back even further in time. Archeological evidence abundantly shows that many prehistoric settlements established themselves near hot springs. ⁶⁸ It’s impossible to prove rock solid that people used those waters for bathing, but why wouldn’t they, especially in cold regions? ⁹

Enjoying a hot bath is a practice that predates recorded history.

Today’s bathing culture relies on fossil fuels, but if we consider the historical context, enjoying a hot bath is not unsustainable. In the case of hot springs, the entire infrastructure and operation — water supply, drainage, and heat source — are already in place.

Our ancestors also invented the steam or sweat bath to take advantage of cold water in all seasons and climates. Rather than heating water, it heats people so they can bathe comfortably in cold water. The earliest steam huts, from prehistoric times, were little more than small log cabins or tent-like structures covered with woolen blankets or hides. ¹⁰¹¹¹²¹³

Painting: Bathing Place, oil on canvas, Paul Gauguin, 1886.

The Birth of the Bathhouse

Artificial bathing facilities made from brick or stone appeared around 4,000 years ago. ¹⁴ They could be an open-air pool, a bathhouse, or a private bathroom. Many bathhouses and bathing pools were built on top of natural hot springs, modifying the natural environment to make it more convenient, safe, and attractive.⁶⁸ People also began to divert water into urban bathing facilities using canals, pipes, and aqueducts. They started building baths that used artificially heated water as well.

The Ancient Romans are most famously associated with the public bathhouse, although they took much inspiration from the Ancient Greeks. Greek bathhouses comprised rooms with individual hip baths against the walls. Sitting up straight, the bathers threw hot water over themselves or had this done by a servant. In contrast, Roman bathers shared the water in large bathtubs or pools. Both used steam baths as well. ¹⁵¹⁶¹⁷¹⁸

At the height of the Empire, there were around 1,000 public baths in the city of Rome alone for a population of about 1 million people - one bathhouse per 1,000 people. ⁸¹⁹ The most prominent bathhouses were the “thermae,” which could hold up to a few thousand people bathing at the same time. These facilities, which only appeared in the largest cities, were richly decorated with mosaics, marble floors and pools, granite columns, and statues. However, most Ancient Roman bathhouses were smaller neighborhood baths called “balnea.” ¹⁵

Image: Cross-section of the Baths of Diocletian by French architect Edmond Paulin, 1880. This bath complex was the largest of Ancient Rome, with a capacity of over 3,000 people.

The Preindustrial Bathhouse

The public bathhouse’s history continues after the Roman Empire’s demise. In the East, the Roman bathhouse evolved into the hammam, which ditched the pools and concentrated more on sweating as a cleaning method.²⁰²¹ After a sweat bath, people threw water over themselves. Reminiscent of the small Roman baths known as balnea, hammams spread in large numbers in all cities of the Islamic world as they facilitated bodily cleanliness and the accomplishment of body ablutions before praying. ²²

In Western Europe, many Roman baths fell into disrepair. However, the public bathhouse returned in full swing during the late Middle Ages, when a new period of urbanization set in. ²³²⁴²⁵ In the 13th, 14th, and 15th centuries, a lot of European cities had a public bathhouse per 2,000 to 5,000 citizens.²⁶ Many were steam baths inspired by the hammam. A second type of bathhouse offered wooden bathtubs to seat a small group of people. The medieval bathhouse was known as a “stew,” which refers to the oven that either heated water for the bathtubs or filled the room with steam. ²³²⁵

Image: A former medieval bathhouse, built in 1562, in Münden, Germany. Photo by Axel Hindemith (CC BY-SA 4.0).

Image: The women's bathhouse, by Albrecht Dürer, 1496.

Painting: Rudas Baths, Ludwig Rohbock, 1850. The Rudas Baths in Budapest were built in 1550 and are still in operation.

Northern Europe and Russia - never conquered by Roman or Islamic Empires - stuck to sweat and hot air baths. For example, public “banyas” existed in towns throughout Muscovy during the Middle Ages. ¹² Asia also developed independent bathing cultures. For instance, in late medieval Japan, people shared private hot baths among families, neighbors, and friends for economic reasons. For these “cooperative baths” of mostly four to ten individuals, every bather brought a portion of firewood to heat the water. That practice evolved into larger public baths - “sento” - which experienced rapid growth from the fifteenth century onwards.²⁷²⁸

Image: Women taking a vapour bath. Wood engraving by Olaf Sörling.

Image: Men in a Japanese bathhouse, early twentieth century. Image in the public domain.

Bathing for Pleasure

Nowadays, sustainability advocates who promote shorter or less frequent showers implicitly regard bathing as a strictly utilitarian practice. However, for most of history, bathing was never just about hygiene. Apart from getting clean, people also visited public baths to relax, have fun, and socialize. Rather than a quick affair, the bathing process — no matter its form — often went on for hours. ¹⁵²⁸

The Ancient Greeks sat together in individual bathtubs, having conversations, for which the space’s acoustics were optimally suited. ²⁹ In Ancient Rome, public baths were places where people went almost daily to be seen, mingle, relax, gossip, dine, or play sports and study. Bathers accessed beauty treatments such as massages, shaving, hairdressing, and depilating. They celebrated parties and anniversaries and honored foreign guests. ¹⁵¹⁷¹⁹²⁵³⁰

Rather than a quick affair, the bathing process — no matter its form — often went on for hours.

The medieval European bathhouse continued these traditions with less splendor but not necessarily with less revelry. In particular, medieval stews with wooden bathtubs were often a place of amusement that also furnished food, drink, music, and various types of bodily care. ²³ In Japan, during the 16th century, public baths became places to gather and socialize, with large groups of people eating, drinking, and singing. ²⁷²⁸ River bathing, which continued around cities and in rural areas until the 20th century, was a kind of play in which swimming was a potential element. ³¹

At the same time, bathing was considered essential to prevent and cure diseases, following the Hippocratic ideas that people could maintain or restore the balance of bodily fluids by exposing the body to cold, hot, moist, or dry circumstances. The layout of preindustrial baths reflected these ideas, featuring pools and spaces of different temperatures. ¹⁵²¹

Image: Miniature drawing in "De Sphaera Mundi", written by Johannes de Sacrobosco, circa 1230.

Playing chess at the Széchenyi Baths in Budapest, Hungary, 1970s. Photo by Kereki Sándor. Found at [Fortepan](https://fortepan.hu/hu/).

Communal Luxury

While these elements of pleasure, social interaction, and health continue today in mineral spas, there is a crucial difference with earlier bathing practices. The present-day spa is far too expensive to substitute for a private bathroom. In contrast, the historical public bathhouse was an egalitarian institution.

Roman public baths had no or low entrance fees and were open to everyone. There were no areas reserved for higher-ranking patrons. Combined with the splendid architecture and opulent decoration of the baths, this ensured that even the most humble servant would have a taste of luxury. ¹⁵¹⁷¹⁹ These customs continued into the European Middle Ages and were shared by bathing cultures across the world. ²³ For example, in Japan, the bathhouse aided in “slowly deconstructing the existing social hierarchy and created a new cultural flow between the elite and the commoners.” ²⁸³²

The only separation happened between men and women, and it was far from universal across space and time. They would either go to different bathhouses, occupy different sections, or share the same spaces at different times of the day or the week. ¹²¹⁵¹⁷¹⁹²³

Image: A sento in Japan. Photo by [Stuart Gibson](https://stuartgibson.aminus3.com/portfolio/).

The Fuel Use of Roman Bathhouses

How sustainable was that communal luxury? Most research about the energy use of bathhouses concerns Ancient Roman baths. Historians have sometimes faulted the large bathhouses from the Empire for their wastefulness, arguing that their widespread use caused deforestation. ³³³⁴³⁵ However, in recent years, archeological research, thermal analysis, and heat transfer studies have made it increasingly clear that Ancient Roman bathhouses, in spite of their opulence, were remarkably energy-efficient buildings. ³⁶³³

The first reason was the hypocaust system. It consisted of one or more underground furnaces that distributed hot air under the floor and into the hollow walls (some baths had heated ceilings, too). Because of the large radiant surfaces, the spaces in the building could be heated at a lower temperature, saving energy. Although the water for the pools was reheated periodically in an insulated boiler close to the furnace, the heat in the floors and the walls helped to keep it warm for an extended period. ³⁶³³

A study of the Stabian Baths, one of the oldest surviving thermae, shows a fuel consumption of between 5 and 8 kg of firewood per hour, depending on the season. ³⁶³⁷ That corresponds to a wood supply of slightly more than 60 ash trees per year, which was unlikely to cause deforestation. ³⁶ Firewood consumption was probably even lower because Roman baths routinely supplemented wood with other locally available fuels, often waste products: reeds, harvest by-products (olive pits, orchard trimmings, chaff), and animal wastes (dung and bones). ³³

Many Roman baths were heated almost exclusively by solar energy on sunny days.

Following the same methodology, a study of a later bathing complex - the Forum Baths in Ostia - shows that the Romans continued improving their bathhouses’ energy efficiency. ³⁸³⁹ The Forum Baths were three times larger than the Stabian Baths - 923m2 versus 310m2 of heated spaces - but their calculated annual wood consumption is not even twice as high: roughly 100 trees per year. ³⁸³⁶ The newer bathhouse had thicker walls (two meters instead of one meter), as well as much larger glazed windows, which increased the share of solar radiation. ⁴⁰ Earlier research has shown that the Forum baths were heated almost exclusively by solar energy on sunny days. ⁴¹

The studies above assume that the Romans heated their baths for 24 hours daily and only shut them down for maintenance. Roman bathhouses likely continued to be heated through the night, as it was more practical and energy-efficient. Many baths were open daily, and it could take a whole day to heat them from a cold state. In later centuries, medieval stews and hammams often used the heat or the ashes of the furnace to bake bread and other foods at night. ⁴² Hammams and medieval stews were less energy-efficient than Roman baths. Hammams had heated floors but no heated walls and few windows, while medieval stews often had none of these.

Image: The large windows of the Forum Baths. Image: [Jan Theo Bakker](https://www.ostia-antica.org/regio1/12/12-6.htm).

Image: The hypocaust of the Great Baths complex, Ancient Dion. Imgae by Carole Raddato (CC BY-SA 2.0).

Image: Historical Reconstruction of the Roman Baths in Weißenburg, Germany, using data from laser scan technology. Credit: [CyArk](https://en.m.wikipedia.org/wiki/File:Cyark_Weissenburg_Reconstruction.jpg#filelinks). CC BY-SA 3.0

Roman Bathhouse Versus Private Shower

How does the energy use of the Roman bathhouse compare to that of the modern shower? Academic research does not provide an answer, but a quick calculation shows that the Roman bathing experience, which lasted for hours, was more energy-efficient than the present-day private shower, which lasts, on average, 9 minutes. The daily energy use of the Forum baths corresponds to the daily energy use of 557 showers. ⁴³ While we don’t know how many people visited the Forum Baths daily, they likely surpassed that number: the baths could host up to 500 bathers simultaneously. ⁴⁴

The Roman bathing experience, which lasted for hours, was more energy-efficient than the present-day private shower, which lasts, on average, 9 minutes.

Furthermore, in the calculation above, the energy use for the shower only concerns water heating, while the fuel use for the public baths also - and mainly - includes space heating. ³⁶ For example, assuming that the water in the pools of the Stabian baths was changed only once per day, heating the water accounted for less than 10% of the total energy use, corresponding to the energy use of only 52 showers. The low energy use for water heating is partly explained by the excellent thermal insulation of the heated floors and walls, meaning that space and water heating cannot be separated. However, it is also because the Romans shared the water in pools, while every shower requires freshly heated water.

The Roman bathhouse also compares favorably to the typical backyard sauna, for which the fuel consumption hovers between 5 and 15kg of firewood per session. ⁴⁵ Only sixteen such sauna sessions require as much fuel as the Stabian baths used daily. The sauna has no heated floor and walls. Furthermore, historically, it was often built partly underground to save fuel, but nowadays, it’s usually a badly insulated building standing in a cold climate.

Image: Bathing sandals for women, Saudi Arabia. Heated floors of hammams were too hot to walk on barefoot. Source: [Wereldmuseum](https://collectie.wereldmuseum.nl/) (CC BY-SA 4.0).

The Public Baths of the Industrial Revolution

Bathing practices have changed quite a lot since Roman and late medieval times, particularly in most of the Western world. Few of us will have the time or even the need to linger in a bathhouse for several hours daily, and some of us may feel uncomfortable bathing in public. ³⁰ However, a bathhouse can also take a form more in line with modern bathing habits. The public bathhouse of the Industrial Revolution demonstrates this.

In the nineteenth and early twentieth centuries, cities received large numbers of immigrants who came to work in factories. Most of these people were housed in overcrowded tenement buildings without running water, leading to unsanitary conditions. ⁴⁶ Recurring epidemics and new medical insights led to a “gospel of cleanliness” that resulted in a new wave of public bathhouses across the Western world. Many of these baths only disappeared between the 1950s and 1980s.

The public hygiene movement began in England and peaked there in the 1840s. By 1896, more than 200 municipalities in Britain were maintaining public baths. The English bathhouse emulated the splendor of Roman baths in its architecture and decoration: it was “large, handsome, and costly.” ⁴⁶ However, it did not copy the Ancient bathing customs. It now reserved different sections of the bathhouse for different social classes. Furthermore, while the pools still provided social interaction, the bathtubs were now placed in individual compartments. Finally, the modern bathhouse instituted maximum time limits for using the pool and the bathtubs. ⁴⁶⁴⁷⁴⁸

Image: Nechelles public baths in Birmingham, England, 1910. Image by Oosoom (CC BY-SA 3.0).

Image: The restored interior of the Amalienbad in Vienna, Austria, built in 1926. It was one of the largest bathhouses in Europe at the time, holding up to 1,300 bathers simultaneously. The original roof could slide open in good weather. Image by Schwimmschule Steiner (CC BY-SA 4.0).

The Shower Bathhouse

Germany, the first to follow the British on the continent, also built monumental bathhouses. ⁴⁹ However, in the 1880s, Berlin physician Oscar Lasser argued that the large baths were too costly to build in the necessary numbers. He proposed the introduction of smaller bathhouses with nothing but showers in individual compartments. Until then, the shower was only attached to a bathtub or used in barracks and prisons, where soldiers and inmates were showered with cold water. ⁴⁸⁴⁶²⁵

The shower bathhouse became the dominant public bath type in most of Western Europe and also in North America, where the sanitary reform movement took off in the 1890s. ⁵⁰⁵¹ It cleared away the last vestiges of the Ancient bathing culture by ditching the pools and switching to a more practical architecture. For better or worse, the public bathhouse from the Industrial Revolution was the “antithesis of the preindustrial bathhouse.” ⁴⁷ Although bathers still made use of communal infrastructure, there was no more space for pleasure, social interaction, public nakedness, and social mixing.

For better or worse, the public bathhouse from the Industrial Revolution was the antithesis of the preindustrial bathhouse.

As the higher social classes gradually gained access to their private water supply and bathrooms, the public bath became increasingly associated with poverty. Although shower bathhouses did not have separate sections for different social classes, they were mainly built in low-income neighborhoods, aimed at the poor only. Bathers were led to their shower cubicle by an attendant, who opened the tap, decided on the water temperature, and started a timer. People had at most 20 minutes to undress, shower, and dress again.⁴⁶⁴⁷ “The poor had to be clean but not enjoy it too much.” ⁴⁶

Image: The last bath attendant of a bathhouse in Haarlem, the Netherlands, in 1984. Image in the public domain.

Bath and shower rooms equipped with timers in Amsterdam bathhouses, 1985. Source: [Stadsarchief Amsterdam](https://archief.amsterdam/beeldbank/detail/ca27031b-8e92-023a-eb42-461dc0cf6fd2/media/728f468c-3dca-91e3-0eb9-6dca39ea8130?mode=detail&view=horizontal&q=badhuis&rows=1&page=24).

Image: Shower cubicles in a municipal bathhouse in Amsterdam, the Netherlands. Stadsarchief Amsterdam.

Image: Boiler room of a municipal bathhouse in Amsterdam, the Netherlands, 1985. Stadsarchief Amsterdam.

Bring Back the Public Bathhouse?

In Europe and North America, the public bathhouse disappeared once everyone got their private bathroom - although we still bathe together in sports centers and continue using communal bathrooms in hostels or campings. The public bathhouse survives elsewhere but is in decline almost everywhere. For example, Cairo had only eight hammams in 2000, compared to more than seventy at the beginning of the 19th century.⁵²⁵³ In 1968, greater Tokyo boasted 2,687 public bathhouses. In 2022, only 462 were left. ⁵⁴⁵⁵

Historically, the bathhouse was born out of the need for efficiency: bathing was too resource-intensive to organize individually. That is no longer the case thanks to the advance of central infrastructures - fossil fuels, electricity, water supply, sewers. However, in the context of the present environmental crisis, the resource efficiency of the public bathhouse has become relevant once again. It’s a solution that could reduce energy use relatively quickly without the need for new technologies or sacrificing comfort. Resilience is another argument for the bathhouse. ⁵⁶

Image: Municipal bathhouse at Javaplein in Amsterdam, the Netherlands. Image: Stadsarchief Amsterdam.

Image: A former bathhouse in Flensburg, Germany. Image: VollwertBIT (CC BY-SA 2.5).

What Type of Public Bathhouse Do We Want?

The metamorphosis of the public bath in the 19th and 20th centuries, which also affected public baths outside the Western world, presents a challenge to anyone wanting to revive public bathing for sustainability. What type of bathhouse do we want? Of course, the Roman bath and the shower bathhouse are both extremes, and many intermediate forms are imaginable. Nevertheless, any designer of a future bathhouse will have to make decisions that are likely to be controversial.

For example, one could argue that the shower bathhouse not only fits modern bathing practices but also maximizes resource efficiency. That is especially true when the government, rather than the bather, controls shower duration and water temperature. In that way, the public bathhouse could become a technology to enforce frugality upon the whole population. However, to put it mildly, such an approach is unlikely to generate enthusiasm for reviving public bathhouses. Neither does it do much to improve social interaction. ⁵⁷

Any designer of a future bathhouse will have to make decisions that are likely to be controversial.

Advocating for the return of the preindustrial public bathhouse, which centers around social interaction and communal luxury, may be more successful in luring people away from their private bathrooms, but it also runs into obstacles. The public bathhouse has faced resistance for 2,000 years, mostly because of conflicting views about health and morals. ⁵⁸ For example, concerns about debauchery and prostitution - real and imagined - run throughout the history of the bathhouse in all cultures. ⁵⁹ Separating males and females does not fully address those worries.

Image: Scene of a bathhouse, c. 1470, painted by the Master of Anthony of Burgundy (Berlin Staatsbibliothek, Ms. Dep. Breslau 2, vol. 2, fol. 244).

Any plea for reviving public baths will also have to deal with the fear of contagious disease. For example, a “lockdown” of society, as many governments applied during the coronavirus pandemic in 2020 and 2021, is incompatible with public bathhouses. Such a measure only works when everybody has a private bathroom. ⁶⁰ The link between communal bathing and health is complex. Science has confirmed many of the health benefits of cold, hot, and steam baths and has also shown the importance of social interaction. However, bringing people together will always raise health risks, too.

How to Build a Low-tech Bathhouse?

There’s another distinction between bathhouses built before and after the Industrial Revolution: preindustrial baths worked with renewable fuels, while industrial baths ran on fossil fuels. Many modern bathhouses had an on-site coal power plant, which heated the space and the water and provided electricity for lighting. Fossil fuel-powered bathhouses are more energy efficient than fossil fuel-powered private bathrooms, but we can do better than that.

A large bathhouse heated by a hypocaust system and large windows is still hard to beat as a carbon neutral technology, at least based on sustainable wood production. ⁶¹⁶² However, biomass combustion creates air pollution, while we could also power a bathhouse with renewable energy sources that don’t have that problem. The most apparent solution for space and water heating is flat plate solar collectors in which the sun heats water. Heat-generating windmills are a low-tech alternative to solar thermal collectors in less sunny climates. ⁶³ Other potential heat sources are geothermal energy and factory waste heat.

Fossil fuel-powered bathhouses are more energy efficient than fossil fuel-powered private bathrooms, but we can do better than that.

A solar or wind-powered bathhouse’s biggest drawback is its dependency on favorable weather conditions. To compensate for that, solar or wind power can be combined with thermal energy storage, such as insulated water tanks. Storing heat in a thermal mass for longer periods is much cheaper and more sustainable than storing electricity in chemical batteries. However, it requires space that only communal bathing can offer. Steam baths and saunas are more difficult to disconnect from biomass combustion, but some innovative examples exist. ⁶⁴

Clustering bathing facilities in a shared infrastructure also creates sufficient space for a bathhouse to have extensive heat insulation (a decisive factor in energy consumption) and provide for its water supply (for example, by catching and storing rainwater) as well as wastewater treatment (for example through phytoremediation using plants).

Architects have applied some of these ideas in countries where public baths are still used. For example, in a mountain village in China, a community bathhouse for 5,000 people is largely off-the-grid, pumping up its water from a well, heating it with solar collectors, and filtering the run-off wastewater from the showers and the toilets in basins filled with bamboo plants. ⁶⁵

Image: This bathhouse in China has 24 showers and serves a community of 5,000 residents. It recycles the waste-water with bamboo plants. Source: BAO Architects.

However, a public bathhouse also fits the more high-tech vision of a centralized energy infrastructure based on solar PV panels and wind turbines that provide electricity. In such a configuration, public bathhouses could absorb excess electricity during abundantly sunny or windy days. Rather than curtailing the electricity from surplus solar and wind power, we could use it to power electric heat pumps and store the heat in the thermal mass of public baths. ⁶⁶ While this approach is less resource-efficient than off-grid bathhouses operating without electricity, it still beats a scenario in which a centralized renewable power grid supplies energy to many private bathrooms.

Kris De Decker

Many thanks to Jonas Görgen and Elizabeth Shove for their feedback on an earlier version of this article.

Marie Verdeil and Roel Roscam Abbing contributed to the selection of images.

The spread of water supply and sewer networks took a lot of time, especially in older European cities. Before 1900, only the most expensive Paris flats had a bathroom. ²⁶ Plumbed-in private baths appeared in the wealthiest British households in the 1860s. Still, it was not until the 1950s that working-class homes were routinely supplied with hot and cold running water. ³ In the newer cities of the USA, installing a water supply and sewer infrastructure was easier. From the 1870s, American plumbing outstripped that of every other country. More than half of all American houses had a complete bathroom in 1940. For comparison, in the whole of France, only one house or apartment in ten had a shower or bath in 1954. ²⁰ ↩︎
Mist Showers: Sustainable Decadence?, Kris De Decker, Low-tech Magazine, 2019. https://qelnixcor.cloud/2019/10/mist-showers-sustainable-decadence/ ↩︎ ↩︎ ↩︎ ↩︎
Pickerill, Jenny. “Cold comfort? Reconceiving the practices of bathing in British self-build eco-homes.” Annals of the Association of American Geographers 105.5 (2015): 1061-1077. https://www.tandfonline.com/doi/full/10.1080/00045608.2015.1060880 ↩︎ ↩︎ ↩︎
The trend is towards more and longer showers ² and more, larger and more luxurious private bathrooms. For example, more than one-third of new single-family homes in the US had three or more bathrooms in 2021, compared to “only” a quarter in 2005. Source: Number of Bathrooms in New Homes in 2021, Jesse Wade, National Association Of Home Builders, November 2022. https://eyeonhousing.org/2022/11/number-of-bathrooms-in-new-homes-in-2021/ ↩︎
How much water public bathing can save depends on how exactly people bathe together. Shared pools and bathtubs bring water savings, but individual showers and bathtubs do not, even if placed in a communal space. ↩︎
Erfurt, Patricia. “Hot springs throughout history. The Geoheritage of hot springs.” Cham: Springer International Publishing, 2021. 119-182. ↩︎ ↩︎ ↩︎
Tamburello, Giancarlo, et al. “Global thermal spring distribution and relationship to endogenous and exogenous factors.” Nature Communications 13.1 (2022): 6378. ↩︎
Cataldi, Raffaele, Susan F. Hodgson, and John W. Lund. Stories from a heated earth: our geothermal heritage. No. 19. Nicholson, 1999. ↩︎ ↩︎ ↩︎
Even some animals - like snow monkeys and capybaras - are known to enjoy bathing in hot springs. See, for example: Matsuzawa, Tetsuro. “Hot-spring bathing of wild monkeys in Shiga-Heights: origin and propagation of a cultural behavior.” Primates 59.3 (2018): 209-213. https://link.springer.com/content/pdf/10.1007/s10329-018-0661-z.pdf. ↩︎
Sonntag, C. F. “The History of Baths and Bathing in Britain before the Norman Conquest.” Proceedings of the Royal Society of Medicine 13.sect_hist_med (1920): 25-46. ↩︎ ↩︎
Aaland, Mikkel. “Sweat: The illustrated history and description of the Finnish sauna, Russian bania, Islamic hammam, Japanese mushi-buro, Mexican temescal and American Indian & Eskimo sweat lodge.” (1978). ↩︎
Pollock, Ethan. Without the banya we would perish: a history of the Russian bathhouse. Oxford University Press, USA, 2019. ↩︎ ↩︎ ↩︎
The first written reference to the steam bath dates back to the fifth century BC, when Greek historian Herodotus compared the Scythian sweat bath north of the Black sea to the Greek steam bath of his time. However, it’s very likely that its origins go back to prehistoric times. Not surprisingly, the steam bath and the hot air bath initially spread in regions with cold and long winters: northwestern Europe, Russia, Alaska, and Canada. It was also used by Native Americans, and spread to Central and South America as well. ¹⁰ ↩︎
One of the earliest archeological records of human-made bathing facilities dates back to around 2300 BC in what is now Pakistan. The inhabitants of Mohenjo-daro, the probable capital of the Indus civilization, built wells and drainage systems allowing for private bathrooms in most residential buildings, as well as a large, communal bathing pool. The private bathrooms had a 1m2 shallow platform, where people threw buckets of water over themselves. The “Great Bath” was a brick basin with steps on either side and a capacity for 160 m3 of water. As the city was located in a hot desert climate, there was no need for heating the water. Sources: Graeber, David, and David Wengrow. The dawn of everything: A new history of humanity. Penguin UK, 2021 + Jansen, Michael. “Mohenjo-Daro, Indus Valley civilization: water supply and water use in one of the largest Bronze Age cities of the third millennium BC.” Geo: A new world of knowledge (2011). https://openarchive.icomos.org/id/eprint/1541/1/110601geo_06_2011_indian_edition_email.pdf ↩︎
Maréchal, Sadi. Public baths and bathing habits in Late Antiquity: a study of the archaeological and historical evidence from Roman Italy, North Africa and Palestine between AD 285 and AD 700. Diss. Ghent University, 2016. https://biblio.ugent.be/publication/7235534/file/7235545.pdf ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Fagan, Garrett G. “The genesis of the Roman public bath: recent approaches and future directions.” American Journal of Archaeology 105.3 (2001): 403-426. ↩︎
Kosso, Cynthia, and Anne Scott, eds. The nature and function of water, baths, bathing, and hygiene from antiquity through the Renaissance. Vol. 11. Brill, 2009. ↩︎ ↩︎ ↩︎ ↩︎
Both the Greeks and the Romans also used cold baths in combination with sports facilities. Here, the act of washing was secondary. ¹⁵¹⁹ ↩︎
Hoagland, Alison K. The bathroom: a social history of cleanliness and the body. Bloomsbury Publishing USA, 2018. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Ashenburg, Katherine. The dirt on clean: An unsanitized history. Vintage Canada, 2010. ↩︎ ↩︎ ↩︎
Fournier, Caroline. Les bains d’al-Andalus: VIIIe-XVe siècle. Presses universitaires de Rennes, 2018. https://books.openedition.org/pur/44617#anchor-resume ↩︎ ↩︎ ↩︎
Sibley, Magda, Camilla Pezzica, and Chris Tweed. “Eco-hammam: the complexity of accelerating the ecological transition of a key social heritage sector in Morocco.” Sustainability 13.17 (2021): 9935 ↩︎
Coomans, Janna. “Janna Coomans - The Medieval Bathhouse (MA Thesis - 2013).” The Medieval Bathhouse: Bathing Culture in the Late Medieval Low Countries (2013): n. pag. Print. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Wurtzel, Ellen. “Passionate Encounters, Public Healing: Medieval Urban Bathhouses in Northern France.” French Historical Studies 46.3 (2023): 331-360. https://read.dukeupress.edu/french-historical-studies/article/46/3/331/381254/Passionate-Encounters-Public-HealingMedieval-Urban ↩︎ ↩︎
Büchner, Robert. Im städtischen Bad vor 500 Jahren: Badhaus, bader und Badegäste im alten Tirol. Böhlau, 2014. ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Thirteenth century Paris, with 200,000 inhabitants, counted around 30 public bathhouses ²³²⁴, while 14th century London, with a population of 80,000, had at least 18 public baths. ²⁰ In the late 14th century Low Countries, Bruges (30,000 inhabitants) and Ghent (40,000 inhabitants) each had around twenty public baths, while smaller cities like Maastricht and Leuven (15,000 inhabitants) had around five. Vienna (Austria) counted 29 bathhouses in the fifteenth century. ²³ Medieval bathhouses, like hammams, were smaller than Roman baths. Medieval stews found in Germany and the Low Countries had a ground surface of between 100 and 200 square meters. ²³ The typical roman city bath had a surface of about 500 m2. ¹⁵ ↩︎ ↩︎
Butler, Lee. “Washing Off the Dust”: Baths and Bathing in Late Medieval Japan." Monumenta Nipponica 60.1 (2005): 1-41. https://web.archive.org/web/20190818120651id_/http://muse.jhu.edu:80/article/182356/pdf ↩︎ ↩︎
Merry, Adam M., “More Than a Bath: An Examination of Japanese Bathing Culture” (2013). CMC Senior Theses. Paper 665. http://scholarship.claremont.edu/cmc_theses/665 ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Gill, A. A. ““Chattering” in the Baths: The Urban Greek Bathing Establishment and Social Discourse in Classical Antiquity.” (2011). https://tobias-lib.ub.uni-tuebingen.de/xmlui/bitstream/handle/10900/61481/CD27_Gill_CAA2008.pdf?sequence=2&isAllowed=y ↩︎
Górnicka, Barbara. Nakedness, shame, and embarrassment: A long-term sociological perspective. Vol. 12. Springer, 2016. ↩︎ ↩︎
A Cultural History of Parson’s Pleasure, George Townsend, PhD, Birkbeck, University of London, 2022, unpublished. See also: Dive in! A history of river swimming in Oxford. Museum of Oxford, expo 2023. https://moxdigiexhibits.omeka.net/exhibits/show/dive-in#:~:text=Dive%20In!-,A%20history%20of%20river%20swimming%20in%20Oxford,places%20for%20bathing%20and%20swimming. ↩︎
The egalitarian nature of the public bath was reinforced by the fact that people were partly or completely naked. “One stripped not only of their clothes but also of their social rank and material wealth, which become largely invisible”, concludes a historian of the Japanese public bath. ²⁸ “The true collective is a naked collective”, observes another, referring to the Russian banya. Source: Gearsimova, A. “My Banya, Your Banya: From Reality to Myth.” (2016). ↩︎
Mietz, Michael. “The fuel economy of public bathhouses in the Roman Empire.” Master’s thesis, Ghent University, Faculty of Arts and Philosophy, Campus Boekentoren, Blandijnberg 2 (2016): 9000. https://libstore.ugent.be/fulltxt/RUG01/002/303/996/RUG01-002303996_2016_0001_AC.pdf ↩︎ ↩︎ ↩︎ ↩︎
Wilson, A (2012) Raw materials and energy, in “The cambridge companion to the roman economy, scheidel 2012. ↩︎
Ancient deforestation revisited, Journal of the history of biology, 44 (1), 43-57. https://www.researchgate.net/profile/J-Donald-Hughes/publication/45407393_Ancient_Deforestation_Revisited/links/08ce17d911d2244431641d70/Ancient-Deforestation-Revisited.pdf ↩︎
Miliaresis, Ismini. “Heating the Stabian Baths at Pompeii.” Curious (2021): 83. https://library.oapen.org/bitstream/handle/20.500.12657/58973/1/external_content.pdf#page=91 ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
The study assumes that the baths were heated for 24 hours per day and only shut down for maintenance. The fuel used for heating up the bath initially (calculated at 35 kg in the case of the Stabian Baths) is added only once to the total yearly energy use. The results are also based on the assumption that the water of the baths was changed once per day (and thus had to be heated from a cold state once per day). ↩︎
Veal, Robyn, and Victoria Leitch. Fuel and Fire in the Ancient Roman World: Towards an integrated economic understanding. McDonald Institute for Archaeological Research, 2019. https://www.repository.cam.ac.uk/bitstreams/c349fc20-11d0-4ad4-a2e9-55dccca9f2df/download ↩︎ ↩︎
Miliaresis, Ismini Alexandra. Heating and Fuel Consumption in the Terme del Foro at Ostia. Diss. University of Virginia, 2013. https://libraetd.lib.virginia.edu/public_view/5d86p0445 ↩︎
Whether or not the (small) windows in the Stabian baths had glass or shutters is not entirely clear. The study concludes that energy use is pretty similar with both glazed and unglazed windows. However, the Forum baths, with windows several meters high, would have required almost 1.5 times more wood to heat rooms with unglazed windows during the month of May, and more than twice as much in the coldest month. ↩︎
Ring, James W. “Windows, baths, and solar energy in the Roman empire.” American Journal of Archaeology 100.4 (1996): 717-724. ↩︎
This may have been true for Roman bathhouses as well, but I could not find any reference to it. For hammamns, see, for example: Sibley, Magda, and Martin Sibley. “Hybrid transitions: combining biomass and solar energy for water heating in public bathhouses.” Energy Procedia 83 (2015): 525-532. ↩︎ ↩︎
A fuel use of 7.5 to 12 kg/hr averages at 9.75 kg/hr, which corresponds to 234 kg firewood per day. One kg of wood contains roughly 5 kWh of thermal energy, which brings the daily fuel use of the Forum baths to 1,170 kWh. A shower of 8.9 minutes (the average in the netherlands) takes 2.1 kWh of thermal energy. ² Conclusion: the daily energy use of the Forum Baths equals that of 557 showers. The daily fuel use of the smaller and less energy efficient Stabian baths corresponds to the energy use of 378 showers. ↩︎
Brünenberg–Jens-Arne, Monika Trümper–Clemens, et al. “Stabian Baths in Pompeii. New Research on the Development of Ancient Bathing Culture.” (2019). https://www.academia.edu/download/67567783/Truemper_et_al._Stabian_Baths_RM_2019.pdf ↩︎
The energy use of a sauna is more variable than the energy use of a shower, and I could not find any reliable academic research. The data I use are a rough estimation based on numbers that I found on internet forums and websites. Also note that climate explains part of the difference in energy efficiency: the sauna is often located in a cold climate, while most Roman baths stood around the Mediterranean. ↩︎
Williams, Marilyn T. Washing” the great unwashed": public baths in urban America, 1840-1920. Ohio State University Press, 1991. https://kb.osu.edu/bitstream/handle/1811/6282/1/Washing_the_Great_Unwashed.pdf ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Dillon, Jennifer Reed. Modernity, sanitation and the public bath: Berlin, 1896–1933, as archetype. Duke University, 2007. https://dukespace.lib.duke.edu/bitstreams/33e2fe84-16ec-4044-91d6-75d5c87d37e3/download ↩︎ ↩︎ ↩︎
Ladd, Brian K. “Public baths and civic improvement in nineteenth-century German cities.” Journal of urban history 14.3 (1988): 372-393. ↩︎ ↩︎
The Stuttgart Bathhouse, for example, had two large pools, 300 dressing rooms, 102 bath tubs, two Russian-Roman baths, two cold water baths, a sun bath, and a bath for dogs. By the end of the century, almost every German city had erected at least one monumental bathhouse, which often included a restaurant and barber shop as well. ²⁵⁴⁶ ↩︎
New York City built 25 monumental bathhouses, and Boston included swimming pools and gymnasiums. However, other American cities exclusively built shower bathhouses for the poor classes. For example, by 1920, Chicago had erected more than twenty shower bathhouses throughout the poor and working class districts. ⁴⁶ ↩︎
Germany and Austria built shower bathhouses in poor neighbourhoods but also continued to build elaborate and expensive facilities for the higher social classes, many of them having a water supply but still lacking bathrooms. ⁴⁶ ↩︎
Talmisānī, Mayy, and Eve Gandossi. The last hammams of Cairo: a disappearing bathhouse culture. American Univ in Cairo Press, 2009. ↩︎
Damascus went down from 40 hammams in the 1940s to 13 in 2004. Source: Sibley, Magda. “The Historic hammāms of Damascus and Fez: lessons of sustainability and future developments.” The 23rd conference on passive and low energy architecture (PLEA). 2006. https://www.academia.edu/download/52232181/The_Historic_Hammms_of_Damascus_and_Fez_20170321-32624-5s2lbk.pdf Morocco is an exception. Various sources present different numbers for operating hammams which vary between 6,000 and 10,000 hammams that still operate using the traditional heating system. ⁴² ↩︎
“Tokyo starts effort to revive public bathhouses”, Julian Ryall Tokyo, October 1, 2022. https://www.dw.com/en/japan-launches-campaign-to-revive-fading-public-bathhouses/a-63282747#:~:text=In%20an%20effort%20to%20protect,pop%20into%20their%20local%20bathhouse. ↩︎
“Public baths fade from Tokyo, with nearly half gone over 15 years”, Natsumi Nakai, October 10, 2023. https://www.asahi.com/ajw/articles/15025294#:~:text=Public%20bathhouses%20are%20swiftly%20disappearing,to%20the%20Tokyo%20metropolitan%20government. ↩︎
“Fuel Crisis Forces Syrians to Use Public Baths”, Sputnik International, 2023. https://sputnikglobe.com/20230131/fuel-crisis-forces-syrians-to-use-public-baths-1106687250.html See also: “Aleppo bathhouse boom as Syria crisis turns showers cold”, Africanews, 2021. https://www.africanews.com/2021/12/30/aleppo-bathhouse-boom-as-syria-crisis-turns-showers-cold/ ↩︎
“Why we need to bring back the art of communal bathing”. Jamie Mackay, Aeon Magazine, 2016. https://aeon.co/ideas/why-we-need-to-bring-back-the-art-of-communal-bathing ↩︎
This is especially true in Western Europe, where opposition grew so strong that the bathhouse eventually disappeared in some regions between the sixteenth and the nineteenth century. ²³ The reasons for the temporal demise of bathing in Western Europe - a unique event in world history - are controversial among historians. Some point to the pressure of the Catholic and Protestant church, who increasingly perceived the medieval stews as places of immorality and sin. ⁵⁹ Others see the cause in epidemics, or point to changing medical views - doctors no longer considered hot water and steam healthy. ²³ Opposition started even before organized religion appeared. Ancient Roman philosopher Seneca was critical of the larger Roman baths and wrote several rants against them. He complained about the noise in the thermae, and accused them of extravagance and hedonism. See, for example: Moral letters to Lucilius by Seneca. Letter 86. On Scipio’s villa. https://en.wikisource.org/wiki/Moral_letters_to_Lucilius/Letter_86 ↩︎
In Ancient Rome, some bathhouses allowed mixed bathing, while others separated male and female bathers. Prostitution was legal, but the fact that a man’s wife had bathed with other men was a legitimate reason for divorce. ¹⁵ In Muslim Spain, substantial fines were assessed to men who either slipped into the bathhouse on days assigned to women, or who were caught spying through the windows of the structure. Women risked their legal rights if they did the same. Abusing a woman in a bathhouse, even verbally, carried the death penalty. See: Powers, James F. “Frontier municipal baths and social interaction in thirteenth-century Spain.” The American Historical Review 84.3 (1979): 649.667. In the Low Countries during the middle ages, authorities distinguished “honest” from “dishonest” stews. To maintain the quality of the “honest” bathhouses, they abolished, mixed bathing, set rules for bathmaids, and made prostitution in the bathhouse illegal. ²³ ↩︎ ↩︎
There’s no doubt that public bathhouses were a vector in historical epidemics. Medical tracts even advised against visiting the bathhouse. However, almost all baths remained open, very likely because they were seen as a service too essential to withdraw. At least, that was the case in the medieval Low Countries and in the Roman Empire, see: ²³²¹ ↩︎
How to make biomass energy sustainable again? Kris De Decker, Low-tech Magazine, September 2020. https://qelnixcor.cloud/2020/09/how-to-make-biomass-energy-sustainable-again/ ↩︎
Moreover, the hypocaust was further improved in the middle ages, meaning that it could be made even more energy efficient than in Roman times. See: Heat storage hypocausts: air heating in the middle ages, Kris De Decker, Low-tech Magazine, March 2017. https://qelnixcor.cloud/2017/03/heat-storage-hypocausts-air-heating-in-the-middle-ages/ ↩︎
Heat your house with a mechanical windmill, Kris De Decker, Low-tech Magazine, February 2019. https://qelnixcor.cloud/2019/02/heat-your-house-with-a-mechanical-windmill/ ↩︎
For example, researchers at the University of Stuttgart have devised a hybrid storage system consisting of a pressurized water and steam tank that serves as a storage for solar energy. The steam can be released in a sauna anytime, while the water serves to heat the space. See: Schaefer, M., et al. “Development of a zero-energy-sauna: Simulation study of thermal energy storage.” Energy and Buildings 256 (2022): 111659. https://www.sciencedirect.com/science/article/abs/pii/S0378778821009439. A very low-tech example is “Solauna”, which works with solar heat alone, basically by building a very large and well-insulated solar box cooker. See: https://www.biopiscinas.pt/en/solar-sauna/. “Lytefire” creates heat and steam by sunlight from mirrors concentrated on a metal plate or a bag of stones. See: https://lytefiresauna.com/en. ↩︎
See: https://www.designboom.com/architecture/bao-split-bathhouse/. Another example is a bathhouse in Eastern Iran, built in 2004, which runs on two solar collector fields (195 m2 total) and two thermally insulated storage tanks (3m3 each). The facility supplies hot water for twelve showers and four baths, serving the hot water demands of 150 people per day. Source: Azad, E. “Design, installation and operation of a solar thermal public bath in eastern iran.” Energy for Sustainable Development 16.1 (2012): 68-73. Researchers are also investigating the combined use of biomass furnaces and solar thermal collectors for hammams in Morocco. See: Krarouch, M., et al. “Simulation of floor heating in a combined solar-biomass system integrated in a public bathhouse located in Marrakech.” IOP Conference Series: Materials Science and Engineering. Vol. 353. No. 1. IOP Publishing, 2018. See also: Mohamed, Krarouch, and Haller Michel. “Design optimisation of a combined pellets and solar heating systems for water heating in a public bathhouse.” Energy Reports 6 (2020): 1628-1635. See also: Sibley, Magda, Camilla Pezzica, and Chris Tweed. “Eco-hammam: the complexity of accelerating the ecological transition of a key social heritage sector in Morocco.” Sustainability 13.17 (2021): 9935. See also: Zbaidi, Mourad, et al. “Improving the Energy Efficiency of a Traditional Hammam by Using Two Types of Heat Exchanger.” International Journal on Engineering Applications 11.6 (2023). ↩︎
How (Not) to Run a Modern Society on Solar and Wind Power Alone, Kris De Decker, Low-tech Magazine, September 2017. https://qelnixcor.cloud/2017/09/how-not-to-run-a-modern-society-on-solar-and-wind-power-alone/ See also: Battery Killers: Grid-Interactive Water Heaters, Kris De Decker, No Tech Magazine, May 2015. https://www.notechmagazine.com/2015/05/battery-killers-grid-interactive-water-heaters.html ↩︎

Fascine Mattresses: Basketry Gone Wild

Wed, 03 Nov 2021 00:00:00 +0000

Image: Sinking of a fascine mattress for the drainage sluices at Den oever. Source: Dienst Zuiderzeewerken, CC BY 3.0 NL. Date unknown.

Coastal and River Defences

Climate change is an imminent threat to highly populated coastal and river communities worldwide. For centuries, people have built defence structures to prevent floods and erosion: seawalls, bulkheads, breakwaters, groins, levees, dykes, and revetments. Nowadays, we usually build these structures at least partly from energy- and carbon-intensive materials: reinforced concrete (most commonly), geotextiles, steel, wire mesh, asphalt. However, people can and did build very adequate river and coastal defences without adding to environmental destruction in the longer term.

Inspiration comes – not surprisingly – from the Netherlands. The sea has been a threat in the Low Countries since long before climate change. The Dutch built their country partly at the bottom of the sea, drained it with windmills, and surrounded the new land with dykes. The Dutch coast has fine-grained, sandy soil that offers little resistance to the friction of the water. Currents, waves, and propellers of ships scour the bottom and can easily lead to the collapse of dykes, banks, quays, locks, and abutments.

Image: dyke collapse in Zeeland, near Kats on North Beveland, 1966. Public domain.

The Fascine Mattress

With stagnant or slow-flowing fresh or brackish water, planting reeds on the waterline can protect riverbanks. However, this approach doesn’t work with saltwater, nor does it prevent damage from large waves. At least 400 years ago, the Dutch came up with a solution: the fascine mattress. A fascine mattress consists of thousands of fine twigs, mainly from willow trees. These are woven together into a sturdy mat dropped at the bottom of a canal, estuary, or river. A fascine mattress can lay partly on the river-bank or dyke.

Fascine mattresses were often rectangular and of large dimensions: usually between 20 and 30 metres wide and up to 150 metres long (sometimes more). The structures were made on land, towed to their location, and then sunk to the bottom by weighting them with rubble. Everything happened by hand. Nearby coppice plantations supplied the wood for braiding the mattresses.

Image: The making of a fascine mattress, Haringvliet, 1956. Public domain.

Life Expectancy: Centuries

It’s not clear when exactly the Dutch started using fascine mattresses. The oldest image is a 1676 painting by Matthias Withoos, which illustrates the repair of a dyke. However, there are references to brushwood constructions in hydraulic engineering already in the sixteenth century. Many fascine mattresses remain functional today, centuries after their construction. Willow wood becomes rock-hard underwater and almost doesn’t deteriorate. Research in the late 1960s showed that most fascine mattresses submerged for more than 100 years – some dating from the early 1820s – remained intact.

We don’t know how many fascine mattresses are still performing their duties at the bottom of the Dutch waters, but they are basically everywhere. Most data is available from the period following World War II when the Dutch used the technology on a large scale. In 1953, catastrophic flooding hit the Netherlands. That led to the Delta Works, a series of ambitious construction works to protect the land from the sea.

Image: Fascine mattresses in the biesbosch, 1968. Public Domain.

Fascine mattresses were an essential part of this plan. For example, between 1960 and 1966, the Dutch added 200,000 m2 of fascine mattresses in the Wadden area (a group of islands in the north). Between 1954 and 1967, during works on the rivers throughout the country, they sank 1,200,000 m2 fascine mattresses to the bottom.

Braiding a Fascine Mattress

Making a fascine mattress was a craft that mainly involved knotting and braiding. In tidal areas, the Dutch braided fascine mattresses on mudflats that were dry at low tide. This meant that the work had to happen quickly. When the high tide came in again, the structure started floating – and it had to be sturdy enough not to drift apart. Finishing the fascine mattress could happen during the next low tide or even while the structure was floating.

The craftsmen started weaving brushwood into bundles or strips called fascines (“wiepen” in Dutch). Fascines were up to 50m long, had a diameter of about 30-50 cm, and were tied together with thin twigs. The fascines served to build a lower framework, which formed the basis of the entire structure. The bundles were superimposed crosswise about a meter apart and secured with rope and a pole at the crossings.

On top of this framework came a 30-40 cm “filling” of two layers of brushwood across each other. In between these came a reed layer, which made the fascine mattress sand proof. Next, an upper framework of fascines was built, identical to the lower framework, on top of the “filling”. The men then lashed the whole thing to the posts. It took about six men to build 100m2 fascine mattress.

Image: A fascine mattress. By Jan Muijs, Rijkswaterstaat, 1974, CC BY 3.0 nl.

Image: Drawing of a classical fascine mattress made out of willow wood for bed protection of watercourse. Source: Hollands' Rijshout, Van Breen (1920).

Image: Making fascines, 1945. Unknown photographer / Anefo, CC0, via Wikimedia Commons

Image: Making fascines, 1952. Harry Pot / Anefo, CC0, via Wikimedia Commons.

Image: Transporting fascines, 1953. Joop van Bilsen / Anefo, CC0, via Wikimedia Commons.

Image: Braiding fascine mattresses, 1956. Harry Pot / Anefo, CC0, via Wikimedia Commons.

Fences

Next, the craftsmen braided fences on top of a fascine mattress by weaving more brushwood around the poles at the points where the fascines crossed and which protruded well above the upper framework. These fences further reinforced the structure and prevented rubble from rolling off the mattress. That was a risk during the sinking of the fascine mattress. The enclosure also performed its duties when the fascine mattress rested on a steep slope, for instance, a dyke. Smaller stone rubble could also be carried along by the current – fences prevented this. Finally, the men fitted a fascine mattress with drag props (arrangements of seven piles securely tying the ropes) for towing purposes.

Image: Braiding fences on top of a fascine mattress, 1950. By van Oorschot / Anefo, CC0, via Wikimedia Commons.

Image: Braiding the fences. Source: [Zink- en aanverwante werken, benevens het hoe en de wijze waarop](https://repository.tudelft.nl/islandora/object/uuid%3A1ed44c19-ee2a-450d-bc3c-6e377cae54ef), B. Hakkeling, 1970.

Sinking a Fascine Mattress

Once the craftsmen had towed a fascine mattress to its destination and moored it, they sank the structure to the bottom. To this end, the workers weighted the fascine mattress with stone and rubble. This heavy work happened manually. Rows of craftsmen took place on gangways, passing 10 to 30 kg stones one by one. Workers with wheelbarrows transported the rubble from land by wheelbarrows or scooped it straight from a boat onto the fascine mattress.

At sea, one square metre of fascine mattress required roughly 200 kg of stones for sinking. Most weight was placed on the edges to prevent the fascine mattress from tipping over while sinking. Once the structure had reached the bottom, they added another 1,000 kg of heavier stones. On rivers it took less weight: only around 120 kilograms for sinking a fascine mattress and roughly 300 kilograms for keeping it in place. Finding enough stones was a lot more problematic than finding brushwood because they had to be brought in by ship from far away.

Fascine mattresses could only be sunken in a calm sea with little current, so timing was crucial. The slack tide, a period of a few minutes between low and high tide, was exploited to the maximum, even if that meant that work had to be done partly at night.

Image: Workers install fascine matttresses for the construction of locks in the Haringvliet near Hellevoetsluis, 1956. By Anefo, CC0.

Image: Sinking a fascine mattress, 1968. By Nationaal Archief, CC0.

Image: Reinforcing the Vlissingen boulevard, 1958. By Anefo, CC0.

Image: Reinforcing the dyke near Ouwerkerk on Duiveland, 1953. By Joop van Bilsen / Anefo, CC0.

Image: Sinking a fascine mattress. Source: [Zink- en aanverwante werken, benevens het hoe en de wijze waarop](https://repository.tudelft.nl/islandora/object/uuid%3A1ed44c19-ee2a-450d-bc3c-6e377cae54ef), B. Hakkeling, 1970.

Image: Preparing the sinking of a fascine mattress. Source: [Holland’s rijshout](https://repository.tudelft.nl/islandora/object/uuid%3A72029c69-9567-4ad9-8883-ff428cf7d68b), L.G. van Breen, 1920.

Image: Anchoring a fascine mattress. Note the drag prop in the foreground. Joop van Bilsen / Anefo, CC0.

Overlapping Fascine Mattresses

Landing a fascine mattress in the right place was a challenge. It was difficult to sink them with precision. According to some sources, there was often 2-5 metres of space planned between adjacent fascine mattresses. Overlapping structures were to be avoided because the current could overturn the upper piece.

However, Gerrit Jan Schiereck, a retired professor in hydraulic engineering and a former employee of the Dutch public works department, disagrees with this advice: “Contrary to what some books say, it was necessary for fascine mattresses to partly overlap each other”. ¹

Not all fascine mattresses were rectangles. When connecting to existing works, in river bends, and in the case of other irregularities, the structures could take the form of a trapezium or an irregular quadrangle. However, pieces with indented corners were avoided where possible.

Image: Badly dropped fascine mattresses in the bend of a river. Source: [Zink- en aanverwante werken, benevens het hoe en de wijze waarop](https://repository.tudelft.nl/islandora/object/uuid%3A1ed44c19-ee2a-450d-bc3c-6e377cae54ef), B. Hakkeling, 1970.

Image: A collection of fascine mattresses. [Holland’s rijshout](https://repository.tudelft.nl/islandora/object/uuid%3A72029c69-9567-4ad9-8883-ff428cf7d68b), L.G. van Breen, 1920.

Tidal Coppice Plantations

The use of fascine mattresses was closely linked to large-scale brushwood production on coppice plantations. As we saw in a previous article, our forebears harvested wood by lopping trees rather than chopping them. The Dutch coppice plantations – the “grienden” – stand out because of their “wet” soils: high river levels or tidal action occasionally flooded the land. Unlike most other tree species, willow tolerates saltwater and (temporarily) wet feet. As such, the coppice plantations could use land that was not suitable for agriculture.

In 1915, roughly 14,000 hectares (140 km2) of forest in the Netherlands consisted of tidal or river coppice plantations, compared to 85,000 hectares of “normal” coppice plantations, and 155,000 hectares of tall forest. Most lay along estuaries outside the dykes and in the river areas of South Holland and North Brabant. The largest complex was in the Biesbosch. More than 200 different types of willow trees were grown in tidal and river coppice plantations. On impoverished soils, the Dutch planted alder trees between the willow trees. The falling leaves of the alder fertilised the soils and increased the lifespan and production of the willow trees.

Often, a quay surrounded tidal coppice plantations. This kept the water out during a normal tide. The plantation only flooded during storm surges in winter. Valves ensured that the water drained slowly enough to allow the sludge to settle, fertilising the soil. Ditches traversed the plantations and served for drainage – stagnant water was harmful to the trees. The workers also used the narrow canals transporting the brushwood out of the plantations by boats. River coppice plantations were inside the dykes. Here, the groundwater level – influenced by nearby rivers – determined the environment for the trees.

Harvesting the wood was just as labour-intensive as braiding the fascine mattresses. Maintenance was undertaken entirely by hand and concentrated in the winter months. The plantation workers chopped brushwood after the leaves had fallen and tied the branches into bundles. They also put new cuttings in the ground, dredged the ditches, and removed the wood. Most coppice plantation workers were day laborers at a time of the year when there was very little agricultural work. They most often slept in small shelters or on small boats on the plantations. ²

Image: Outer dyke willow field on the Oude Maas (Carnisse Grienden). By Ceinturion, (CC BY-SA 3.0).

Image: The Biesbosch in 1908. Source: [Wilgenkartering in de Brabantse, Sliedrechtse en Dordtse Biesbosch, 2012-2013](http://www.ecologischadviesbureaumaes.nl/429_I.pdf). Nationaal Park de Biesbosch, 2014.

Image: A tidal coppice plantation (Anna-Jacominaplaat) in 1950. Source: [Wilgenkartering in de Brabantse, Sliedrechtse en Dordtse Biesbosch, 2012-2013](http://www.ecologischadviesbureaumaes.nl/429_I.pdf). Nationaal Park de Biesbosch, 2014.

Image: Ditch in a tidal coppice plantation (1930-1950). Source: [Wilgenkartering in de Brabantse, Sliedrechtse en Dordtse Biesbosch, 2012-2013](http://www.ecologischadviesbureaumaes.nl/429_I.pdf). Nationaal Park de Biesbosch, 2014.

Image: A worker's hut on a mound. Source: Regionaal Archief Dordrecht. (CC-BY-SA 4.0).

Houseboat in a tidal coppice plantation. Source: Regionaal Archief Dordrecht. (CC-BY-SA 4.0).

Evolution in the 1960s

Following the catastrophic floods of the 1950s, the Dutch set up a working group to find labour-saving and production-enhancing working methods. The weaving of the fascines, a job that accounted for about a third of all hours in making a fascine mattress, was the first process to be mechanised. A “fascine machine” – running on a 2 HP diesel engine – appeared in 1956. It could make 10,000 fascines per week, supplying enough material for 2,300 m2 of fascine mattresses. From the 1950s, the Dutch also used cranes and vibrating feeders for moving the rubble, and they built wharves to braid the fascine mattresses on large slopes next to the water. That made the construction of a fascine mattress independent of the tides and allowed to organise the work better. The techniques for sinking the structures also evolved.

Finally, the invention of geotextiles as adequate sand filters lowered the need for coppiced wood. This was crucial, because the existing production fields of willow in the country at the time could not supply the quantities needed for the Delta Project. The Dutch tidal and river coppice plantations served different purposes, and fascine mattresses only formed a small market. Much more important were the weaving of baskets and crates, and especially the building of hoops for making herring barrels, an important export product in the Netherlands at the time. Indeed, the Dutch used the waste materials from the hoop-making process to braid fascine mattresses. However, after World War I, iron straps and other packaging materials supplanted hoop-making from the market. Furthermore, fossil fuels made it easier to keep polders dry, so less and less land was available for coppice plantations. Of the 14,000 hectares of tidal and river coppice plantations in 1915, only 2,000 hectares remained in 1983.

The use of traditional fascine mattresses – without geotextiles – disappeared almost completely. However, they are still in use in nature reserves, and have seen renewed interest lately. Producing steel, concrete, and plastic releases carbon emissions and creates other forms of pollution too. On the other hand, traditional fascine mattresses extract carbon from the atmosphere and store it on the seafloor for a couple of centuries – without any pollution or fossil fuels.

Thanks to Gerrit Jan Schiereck, Bart Schultz, and Alice Essam.

References:

De Bruin, Dick, and Bart Schultz. “A simple start with far‐reaching consequences.” Irrigation and Drainage: The journal of the International Commission on Irrigation and Drainage 52.1 (2003): 51-63.

Zink- en aanverwante werken, benevens het hoe en de wijze waarop, B. Hakkeling, 1970.

JW van Westen, Ontwerp en uitvoering van zinkwerken, 1969.

Holland’s rijshout, L.G. van Breen, 1920.

J.A.M. Schepers, Een landelijk overzicht van de grienden, 1988

Getijdenbossen, F.W. Rappard, 1971

Rijshout-, riet- en stroconstructies, J.C Visser 1954

Stroomzinken 1967-1968, H.Y. Wenning

De teelt van griend- en teenhout in nederland en het naburige vlaanderen. DWP Wisboom van Giessendam, 1878.

Geschiedenis van de techniek in nederland. De wording van een moderne samenleving. 1800-1890, deel III. H.W. Lintsen, 1993.

Wilgenkartering in de Brabantse, Sliedrechtse en Dordtse Biesbosch, 2012-2013. Nationaal Park de Biesbosch, 2014.

Phone call on 2 November 2021. ↩︎
As far as I could find out, the large fascine mattress is almost exclusively a Dutch technology. However, Dutch engineers like Johannis de Rijke also introduced the fascine mattress in Japan during the Meiji period (1868-1912). Here, it was made from bamboo. Some years ago, the Japanese still used the technology in the Hokuriku region. River coppice plantations also existed in present-day Belgium (around Bornem) and Poland, but these plantations only supplied basketry materials. ↩︎

Urban Fish Ponds: Low-tech Sewage Treatment for Towns and Cities

Sun, 28 Mar 2021 00:00:00 +0000

Image: Fish ponds in the East Kolkata Wetlands – the largest sewage-fed aquaculture system in the world today. Source: Edwards, 2008. [^8]

After we eat and drink, we excrete into toilets, which use water to flush our effluent into municipal sewage systems. By and large, the resulting sewage is either untreated, or treated in different kinds of wastewater treatment plants, the most advanced of which are expensive to run and have high energy demands. ¹

But even if sewage is treated, effluent is still high in levels of nitrogen, phosphorous, dissolved oxygen, and biological matter—essential nutrients for life on Earth. This causes eutrophication. The high levels of these nutrients lead to algal blooms, which in turn may produce toxins leading to mass fish deaths and biodiversity loss in rivers, lakes, and oceans. ²

Essentially, the core of the issue is that rather than nutrients being recycled, as occurs in most ecosystems, it’s a one-way flow. Fixing these problems by, for example, making water use more efficient, or using more energy-intensive sewage treatment plans, doesn’t solve the root of the problem: the nutrient cycle is leaky. And you can’t fix a leaking sink by changing the amount or kind of water you use.

Too much of a good thing

If we want to fix the leaking sink, we need to move away from the idea that human waste is inherently toxic, or that human activity is always bad for the environment. This way of thinking is grounded in the assumption that humans are somehow separated from nature. The logical conclusion of this assumption, then, is to separate us from natural cycles even more: building more refined, chemically and energy-intensive sewage treatment, building hard boundaries between food production and watersheds, and, failing that, using large-scale geoengineering experiments to clean our rivers.

But the main issue here is not that we are somehow toxic and so a burden to our environment. It’s that the nutrients we are releasing into the environment are too highly concentrated. This is especially the case when it comes to the “problem” of eutrophication. Caused by high-nutrient wastewater and agricultural run-off, it is generally thought as a bad thing. But consider the Greek root of the word: “becoming well fed.”

The main issue is not that we are somehow toxic and so a burden to our environment. It’s that the nutrients we are releasing into the environment are too highly concentrated.

Eutrophication is only bad because good nutrients like nitrogen, carbon, and phosphorous, necessary for the majority of biotic life, are too concentrated—causing rapid algal growth, leading to too little oxygen in the water, as well as too many toxins produced by algae, both of which are deadly to fish. However, fish eat algae, so if algae growth were to be slowed down a bit, fish populations would multiply instead. The problem is not that wastewater is polluted, but that there is too much of a good thing, too highly concentrated for the ecosystem to absorb.

How to fix a leaking sink

I first learned about the system of treating sewage through aquaculture when I lived in Hanoi. There, I found out that it’s actually very common, especially in poor agricultural communities, to reuse human waste for production.

Image: An overhung latrine on a fish pond in Vietnam. Source: UNEP International Environmental Technology Centre. (2002). Environmentally Sound Technologies for Wastewater and Stormwater Management: an International Source Book (Vol. 15). International Water Assn.

In countries like Vietnam and Indonesia, toilets are often placed above fish ponds. Human and livestock waste may also be collected manually and put in fish ponds. Why? Stimulated by the added nitrogen, phosphorous, and carbon, algae and phytoplankton grow rapidly and start breaking down the nutrients and bacteria and produce oxygen. As oxygen levels go up, fish are able to swim in the water and eat the algae and phytoplankton. Then the fish are caught and sold on the market. Finally, when the pond is drained, fish droppings and any remaining sediments can also be used to fertilize surrounding crops, like rice or fruit trees.

In China, the use of excreta in agriculture and aquaculture has a tradition of centuries. During the communist period, many fish farmers had limited access to fish feed and local state cooperatives started organizing human waste collection systems. Eventually, in many Chinese cities, up to the 1990s, trucks and boats collected human manure in cities—some run by the state and some clandestine, illegal operations—and transported them to aquaculture operations in peri-urban land. From 1952 to 1966, about a third of fertilizers (which includes fish feed) used in China came from nightsoils, and by 1966, 90% of excreta were recycled. ³ Incidentally, today, massive seaweed production off the coast of China has likely greatly reduced the likelihood of eutrophication—an accidental form of bio-remediation and nutrient recycling. ⁴

Image: Sewage water being pumped into a fish pond in the outskirts of Hanoi, Vietnam. Source: Edwards, 2005. [^15]

Image: Wastewater after treatment in fishponds, Hanoi. Source: Edwards, 1996. [^5]

One interesting large-scale example is the system that emerged in the outskirts of Hanoi in the 1960s. Hanoi, the capital of the newly independent communist nation, fighting a drawn-out war against Western occupying forces, had no municipal wastewater treatment. Sewage led out into two rivers, which flowed south and eventually merged with the Red River.

During the communist period of collectivization of farmland, Vietnamese farmer cooperatives were excluded from the international market and so often used whatever resources available to them to feed fish, such as slaughterhouse wastes or spoiled grains. Seeing the untreated wastewater in the canals—a resource out of place—farmers started pumping it into large ponds.

Seeing the untreated wastewater in the canals—a resource out of place—farmers started pumping it into large ponds.

After trial and error, and investing the little they had in infrastructural improvements, they determined the right sewage-and-freshwater ratio needed that would dilute the wastewater enough so the fish wouldn’t die.

Image: A local retail fish market in Yen So commune. Anders Dalsgaard. Source: Thi Phong Lan, Nguyen, et al. \"Microbiological quality of fish grown in wastewater-fed and non-wastewater-fed fishponds in Hanoi, Vietnam: influence of hygiene practices in local retail markets.\" Journal of Water and Health 5.2 (2007): 209-218.

Farmers also grew plants such as water hyacinth to reduce the erosion of the banks, and which could then be fed to livestock. These also had the benefit of drawing out heavy metals from the water. They also practiced fish polyculture, where species like catfish, carps, and tilapia were farmed together, and thus were more effective in cleaning the water and protecting small fry from predators. Every year, the ponds were drained, and the sludge at the bottom was then applied to nearby fields, further reusing available nutrients.

Eventually, these farmers developed a system that, by 1995, provided 40-50% of Hanoi’s total fish supply every year. Scientific measurements showed that the water from the fish ponds, when pumped back into the river, was well below the World Health Organisation’s recommended level for biological oxygen demand—an indicator to determine the efficiency of water treatment systems. ⁵ Essentially, they had created a water treatment plant for a city of 1.5 million people, at almost no cost to the state.

A “low-cost folk technology” serving an entire city

You might be thinking: sure, this is one example of an interesting, but ultimately doomed, alternative to wastewater treatment. It is an aberration, and couldn’t possibly be maintained for long. Unfortunately for your internal cynic, it actually can be. The city of Kolkata (formerly Calcutta), India—population 14.8 million—has the largest sewage-fed aquaculture system in the world. Though farmers had been using sewage to feed fish in different ways since the 19th century, the system became more developed starting in the 1940s.

Image: Fish ponds in the East Kolkata Wetlands, the largest sewage-fed aquaculture system in the world today. Source: iStock.

During the British colonial period, administrators built a series of canals through the city that functioned as its sewers. These let out into the Bidyadhari River. However, this river quickly silted up and became unusable. As a result, an adjacent wetland area transformed from tidal salt marshes to primarily freshwater marshes. Two sewage canals were then built in 1940 to further extend the city’s effluent to the ocean. It was at this point that local farmers started rerouting the sewage water into fish ponds in the former salt marshes, growing vegetables on the banks of the sewage canals, and forming cooperatives to manage the wastewater.

Though the Kolkata system was developed over time, it is quite systematic. Every year, ponds are first drained and sludge is applied to fields. Sewage water is fed into the pond slowly at low depth and allowed to sit for two weeks. This basically mimics conventional sewage treatment systems, where sewage is first treated through stimulating algal and bacterial growth, harmful sediments are left to settle, and most parasites are killed because their eggs and worms die if they don’t find a host within two weeks. Then, fish are stocked in another pond, and slowly sewage water is introduced into the pond at a sewage-to-water ratio of 1:4. All of this requires skill and knowledge developed over generations, allowing farmers to know when oxygen levels are too low, which could kill the fish. ³ ⁶ The resulting effluent can reach the water quality of conventional treatment. ⁷

Image: A sluice gate made of bamboo at the Eastern Kolkata Wetlands. Water hyacinth is grown to help purify the water and to feed livestock. Source: Mukherjee, 2020. [^6]

Image: Every year, the ponds are drained, and the sludge at the bottom is applied to nearby fields, further reusing available nutrients. Source: [Take pride in the East Kolkata Wetlands](https://www.facebook.com/takeprideineastkolkatawetlands/) (Facebook-page).

Through trial and error and good judgement, local farmers have developed a wastewater treatment system that is extremely efficient and adaptive to local conditions. They can distinguish the kind of effluent—industrial or domestic—through the hues it gives off, and will control or dilute it when necessary. For example, sewage from tanneries can be toxic to fish, so they will not use it. They vary water levels according to season, weather, and available quantities of effluent. They know the hue of greenish-black the water needs to be to have an optimal oxygen and ammonia level for fish. They can tell whether there is too little oxygen by paying attention to the degree by which fish come up to the surface to gulp air. Farmers harvest snails in the water to protect fish growth, which are then crushed and fed to ducks, whose droppings in turn fertilize fish ponds and nearby soils. They plant water hyacinths and duckweed to absorb heavy metals from the sewage water. ⁷ ⁸

The Kolkata fish farms provide 40% of the region’s fish production and process 80% of the city’s sewage.

The Kolkata fish farms provide 8000 tons of fish per year to the city, or 40% of the region’s fish production. It processes 80% of the city’s sewage, and reduces the nutrient and organic loads of the city’s sewage water by 50-90%, while keeping bacterial loads to an acceptable level under WHO guidelines. It is calculated to save the city an equivalent of $64,400,000 per year in sewage treatment costs—making Kolkata an “ecologically subsidized city”. ⁹ The system provides farmers a return over investment of 28% and provides 200,000 people with a livelihood. ¹⁰

While profit shouldn’t itself be the goal of this system—it’s a public service, after all—it certainly helps to defray costs of wastewater treatment. In a small municipality in Karnal, northern India, one study showed that municipal sewage-fed fish ponds, installed in the 2010s, provided over $25,000 of net profit per year to the municipality, as well as indirect benefits such as improving nearby soils through the sale of treated wastewater to farmers. ¹¹

Image: Waste-fed fish ponds provide steady sources of protein for small-holder farmers. Source: [Fish Farming in the East Kolkata Wetlands, Ramble On, Priya Mallic](https://takeabookalong.wordpress.com/2013/08/12/fish-farming-in-the-east-kolkata-wetlands/).

Image: Fish harvested from the East Kolkata Wetlands. Source: [Fish Farming in the East Kolkata Wetlands, Ramble On, Priya Mallic](https://takeabookalong.wordpress.com/2013/08/12/fish-farming-in-the-east-kolkata-wetlands/).

Still, when introduced into small rural communities, the benefits extend far beyond monetary profit, to the social, cultural, and ecological services provided by the fish ponds. This includes improving soil quality, adaptability of local communities to climate change, leisure (e.g. fishing with friends), and steady sources of protein for small-holder farmers. For example, even if they don’t sell the fish, a small sewage-fed fish pond can provide a family of six with 8kg of fish, per person, per year—a significant raise in protein intake for many rural communities. ¹² In the case of the Eastern Kolkata Wetlands, the fish ponds also help to recharge the ground water—a serious issue in India where many aquifers are nearing depletion. ¹³

Kolkata’s wetlands are a “low-cost folk technology” ¹⁴ treating the majority of the sewage of a city with a population the size of New York. This is made possible through the development of a vast human-fish-plant ecosystem, a city-scale wastewater treatment plant that emerged through the creativity, ecological knowledge, and direction of local farming communities.

Over 90 systems in Germany in the early 20th century

By this point, your internal cynic might have come up with another counter-argument: sure, so it works at scale. But you would have to be pretty desperate, and poor, to stoop down to farming fish in sewage water. While it might work in India, and worked for a while in Vietnam and China, it would never work in developed countries, where there are higher sanitation standards, and where no one would want to eat the fish farmed in sewage anyway.

Image: A view of the former sewage-fed aquaculture system in Munich, Germany, today a bird sanctuary. Photo: Peter Schleypen, 2012. Source: [Historisches Lexikon Bayerns](https://www.historisches-lexikon-bayerns.de/Lexikon/Abwasserbehandlung_(nach_1945))

You may be surprised to learn that, in fact, over 90 such systems existed in Germany in the early 20th century. ¹⁵ Up until the 1990s, the city of Munich still processed most of its wastewater through fish farming. Indeed, Germany has pioneered some of the more detailed and rigorous scientific investigation into the large-scale viability of sewage-fed fish ponds, as early as the 1890s.

Up until the 1990s, the city of Munich in Germany still processed most of its wastewater through fish farming.

Like in China, wastewater-fed fish ponds have a long but unappreciated history in Europe. Castle moats, monasteries, and villages often had wastewater-fed fish ponds. As cities grew rapidly in the 19th century, untreated wastewater was simply flushed into rivers, leading to the collapse of fisheries across Europe as well as generally unsanitary conditions and the spread of disease. There was a growing recognition that sewage should be treated; one common indicator of adequate treatment methods was that trout are able to live in the treated water. As a result, civil engineers and scientists constructed small fish ponds to test the quality of municipal sewage treatment plants.

Gustav Oesten, a civil engineer charged with wastewater treatment in Berlin, began to experiment in the late 1880s with using fish to treat wastewater, and to harvest fish as a secondary product of sewage treatment. He was able to spend the good part of a decade conducting experiments with different fish species, designs for ponds, and various local and weather conditions. ¹⁵

Image: Feed channel for the fish ponds of the Munich sewage-fed aquaculture system. Image by Bjs (CC BY-SA 3.0), Wikimedia Commons.

Through these experiments, he showed conclusively that fish growth accelerates in sewage water, and that fish in turn help purify sewage water. Trout were not very good fish for this purpose, because they cannot tolerate water with high oxygen levels—common in wastewater systems, a byproduct of rapid algae growth. Carp, who can come up for air when oxygen levels are intolerable, grew very well—those fed with sewage far exceeding production of those in normal fish ponds. But, using trout, he proved that the water was of high enough quality to enter back into the water shed. His experiments suggested that fish ponds could be designed to help address Europe’s water crisis and, at the same time, provide an economic return through the sale of fish.

By the beginning of the 20th century scientists throughout Germany started conducting more small-scale experiments. Bruno Hofer, a fish scientist better known for pioneering the study of fish pathologies, started scaling up these experiments, showing in the early 1900s that wastewater of larger institutions like hospitals, breweries, and factories, as well as smaller municipalities could theoretically be treated with fish ponds. He even went further, and “dared” to propose such a system for a city as large as Munich—a notion that was perhaps considered outlandish at the time.

Image: A sprinkler introducing secondary treated wastewater diluted with river water into a wastewater-fed fishpond in Munich, Germany. Source: Edwards, 2005. [^15]

By 1929, however, after several successful implementations of Hofer’s design around Germany, the city of Munich built its own fish pond wastewater treatment system, which served the whole city until the 1990s. This was the largest such system implemented at the time in the world, initially designed to process the wastewater of 500,000 people. The system was so efficient that the water leaving the ponds, fully treated, was comparable to natural water in quality and nutrient level. ¹⁶

Many applications

As these examples illustrate, sewage-fed aquaculture is a solution to many interlinked problems. It processes waste—from agriculture, livestock, and cities—and cycles those nutrients back into the system through food and agricultural production. It reduces nitrogen and phosphorous levels in the water, preventing eutrophication further downstream. It reuses available water, slowing down the water cycle and replenishing groundwater. It further reduces unnecessary inputs like chemical fertilizers, phosphates, and energy-intensive fish feed. Finally, it creates jobs and a source of income, especially necessary in poor countries.

If we were to calculate the fertilizer potential of sewage water alone, this would be reason enough to develop systems to reuse it. For example, one study estimated that, in the year 2000, all of India’s sewage was worth an equivalent of $2,000,000 per day in fertilizer costs. ¹⁷ In other words, on any given day, all of India is flushing several million dollars down the toilet. Waste-fed fish ponds would be of great help in capturing this wealth. Perhaps counter-intuitively, scientists have found that waste-fed fish ponds may actually be especially useful for arid countries, where water is scarce, by re-using wastewater for protein production. ¹⁸ Fish ponds don’t have to be for productive use alone. They can be integrated into wetlands and conservation areas, leisure fishing, tourism areas, or educational sites. They provide opportunities for improving biodiversity and making urban life more permeable for nature.

Fish ponds don’t have to be for productive use alone. They can be integrated into wetlands and conservation areas, leisure fishing, tourism areas, or educational sites.

Another reason waste-fed fish ponds continue to be relevant is that it is low-cost and low-tech, and therefore has little barriers for implementation. While high-tech, high-input systems like hydroponics, vertical gardening, and automated agriculture are getting a lot of press these days, the fact is that the majority of the world’s farmers have little to no access to capital and relies on small, but mostly sustainable, interventions to feed a stunning 70% of the global population. ¹⁹ Waste-fed fish ponds offer a source of subsistence at little financial risk to these small farmers. ⁸ Equally, when developed at the municipal level, they offer small towns, villages, and resource-poor communities opportunities to defray the costs of wastewater treatment, as well as generating local employment and improving sanitation. ¹¹ ¹²

Why don’t we do this more often?

Despite many advantages, most sewage-fed aquaculture systems have either been totally stopped or are in decline. So what happened? The first possible reason, and the one that most people might raise, is the “yuck factor”. Perhaps it’s just too gross for most people to eat fish grown from poop. By and large, this wasn’t the problem: consumers’ surprising acceptance of waste-fed fish is a constant in the research on urban fish ponds. ²⁰ Furthermore, about 10% of the world’s population probably already consumes food irrigated with wastewater ²¹, and, even in the European Union, where agricultural regulations are famously strict, many farmers already apply sewage sludge to their fields—but European consumers don’t seem to care too much.

Image: Tilapia.

Image: Vietnamese catfish.

Image: Common carp.

The second possible reason for their decline is that it’s not safe. And, it’s true, here is where the most care needs to be taken in designing effective wastewater treatment. There is good evidence showing that sewage treatment in fish ponds can be as safe as conventional methods. Some of the strongest evidence to support this comes from a city-sized experiment conducted in the 1980s in Lima, Peru, sponsored by the World Bank and the United Nations Development Project. Aid agencies worked closely together with the city government to design a large-scale aquaponic sewage treatment site. ²²

The site was basically a city-sized proof-of-concept. Endless measurements were taken over its two decades of operation, adjusting different variables throughout the project’s lifespan, and controlling for changes in volume of sewage and weather. It was found quite conclusively that fish-based sewage treatment was not only a viable and economical alternative for low-income countries, it also met stringent World Health Organization guidelines for water sanitation. The fish were also tested for human consumption. In all three trials, 100% of fish tested were rated at “very good” in safety levels. ²³ This study wasn’t alone: numerous studies have investigated the safety of fish grown in sewage ponds. ²⁴

More than just a leaking sink

If it’s not the “yuck factor” or safety, then what was it? In Hanoi, the waste-fed fishponds were not fully recognized for their potential, and peri-urban development in the 1990s began to encroach on the fish ponds. As the communist era came to an end, land near the city became increasingly valuable, and ponds were filled up for housing construction. Sewage became mixed with untreated industrial effluent, leading to large amounts of sewage being poisonous to fish, in turn leading farmers to switch to pelleted feed, by then increasingly available as Vietnam’s domestic market was opened to foreign trade.²⁵ ²⁶ Today, Hanoi only treats 22% of its sewage, the rest flows directly into its river systems, and 180,000 cubic meters of waste water are discharged every day into the To Lich river, the same river that serviced the fish ponds. ²⁷ ²⁸

The disappearance of fish ponds in Germany can also be largely attributed to urban growth. As cities grew, peri-urban areas—where fish ponds necessarily needed to be placed due to them having to be close to sewage lines and sources of fresh water—became more valuable. Pressured by booming real estate prices, less availability of land, high costs of labour, as well as diminishing returns on investment as domestic fish breeding had to compete with international markets, governments inevitably chose to close the fish ponds, or convert them into more conventional sewage treatment plants. Even in Munich, the largest system built in Germany, management was costly and became less and less appealing to the municipality. Munich’s fish ponds were eventually converted into a nature reserve, where migrating birds come to rest. Fish production is no longer its primary goal, and the estuary only absorbs a small percentage of Munich’s wastewater. ¹⁵

Image: The East Kolkata Wetlands in 2005. Source: Google Earth.

Image: The East Kolkata Wetlands in 2019. Source: Google Earth.

The system at Kolkata is still operational, but suffering from similar symptoms. At their peak, fish ponds in the East Kolkata Wetlands were as large as 12,000 hectares. This has shrunk to 4,000 hectares due to encroaching urban development. In Kolkata, too, workers struggle to deal with industrial effluent such as that from the sizeable leather tanning industry, which is poisonous to the fish and indiscriminately dumped into the municipal wastewater system. ⁶ ¹⁰ ²⁹ ³⁰ Thankfully, unlike Hanoi’s government, the city of Kolkata and the Indian government recognized the importance of this system, and put in a series of regulations to protect it from further development. Still, informal and illegal development—where developers fill up ponds with debris overnight and then build on it as farmers are forced to abandon it—is slowly chipping away at the wetlands.

So the main driver of their disappearance is urban expansion into the peripheries. This is largely due to the global speculation on real estate—which constitutes 60% of all capital investments today. ³¹ When given a choice between selling peri-urban land to the highest bidder, and pairing sewage treatment with some fish production, most officials won’t think twice—the fish ponds have got to go! A second reason is the high prevalence of toxic chemicals in our water systems—which are too concentrated for ecosystems, and aquaculture systems, to absorb. We should ask ourselves if it’s really worth it to permit these products if they make it harder for us to mend the ecological rift between our settlements and their surroundings.

More messy, organic systems are often derided as backwards and primitive, when in fact they may be far more appropriate and sustainable than the energy-intensive, easily replicable “solutions” valued by planners and engineers.

A third reason is the relatively cheap cost of fossil fuels. In most industrialized countries, it is much more rational to choose for sewage treatment plans with a small land footprint but a large carbon footprint. In a world where energy is cheap, environmental costs can be pushed further and further downstream. But they will eventually circle back to us, and already are. Finally, a significant factor, and one which we shouldn’t ignore, is the bias of our leaders and of professional engineers against more messy, organic systems like that of wastewater-fed aquaculture. Such low-tech solutions are often derided in popular culture as backwards and primitive, when in fact they may be far more appropriate and sustainable than the energy-intensive, easily replicable “solutions” valued by planners and engineers. ³²

Each reason points to a deeper problem: our economy’s inability to value the right things. Like so many sustainable solutions today, and many of those discussed on this website, sewage-fed fish ponds suffer from the “you can’t change this one thing without changing the whole system” problem. These systems are beset by global real estate speculation, toxic chemicals in our food and household products, contamination by industry, the cheap price of fuel, and the deep-seated idea that humans are separate from the ecosystems they are embedded in. At the root of it all is a system of value that is not in line with our ecological needs as a species, and as a member of Earth’s living community.

Fish ponds are a low-tech, low-cost, safe, and sustainable way to fix our society’s leaking sink. But when we get down there on our hands and knees, we might find a lot of other things that need fixing.

Aaron Vansintjan

Thank you to Henning Fehr for doing research on the fish pond system in Germany, Michael DiGregorio for telling me about the Vietnamese system, Phuong Anh Nguyen for the extra research into it, and Geert Vansintjan for always keeping me inspired.

For example, in many developed countries, sewage treatment often involves constant automated stirring of large ponds of water—a system which is hard to maintain and takes a lot of energy. While sewage treatment only accounts for 4% of national energy use in the US, they account for up to 50% of municipal energy use—a significant portion of the domestic energy footprint. That means that towns and cities could actually decrease their energy impacts significantly if they switched to different treatment plants. See https://betterbuildingssolutioncenter.energy.gov/sites/default/files/Primer%20on%20energy%20efficiency%20in%20water%20and%20wastewater%20plants_0.pdf ↩︎
It also contributes to a little-understood phenomenon called coastal darkening, where our ocean floors become muddier and darker, leading to a lower albedo, or reflectivity, of the Earth’s surface, in turn triggering global heating as well as reduced ability for marine life to receive daylight. https://www.hakaimagazine.com/news/the-environmental-threat-youve-never-heard-of/ ↩︎
Edwards, P. (2003) Philosophy, principles and concepts of integrated agri-aquaculture systems. In: Gooley, G. J., & Gavine, F. M. (Eds.), Integrated agri-aquaculture systems: a resource handbook for Australian industry development. Rural Industries Research and Development Corporation. ↩︎ ↩︎ ↩︎ ↩︎
Edwards, P. (2015). Aquaculture environment interactions: past, present and likely future trends. Aquaculture, 447, 2-14. ↩︎
Edwards, P. (1996). Wastewater reuse in aquaculture: Socially and environmentally appropriate wastewater treatment for Vietnam. The ICLARM Quarterly, January. ↩︎
Mukherjee, J. (2020). Blue Infrastructures. Springer Singapore. ↩︎ ↩︎
Ho, L., & Goethals, P. L. (2020). Municipal wastewater treatment with pond technology: Historical review and future outlook. Ecological Engineering, 148, 105791. ↩︎ ↩︎
Edwards, P. (2009). Traditional asian aquaculture. In New Technologies in Aquaculture (pp. 1029-1063). Woodhead Publishing. ↩︎ ↩︎ ↩︎
A term attributed to Dhrubajyoti Ghosh, a high-profile activist for the Eastern Kolkata Wetlands. ↩︎
Banerjee, S., & Dey, D. (2017). Eco-system complementarities and urban encroachment: A SWOT analysis of the East Kolkata Wetlands, India. Cities and the Environment (CATE), 10(1), 2. ↩︎ ↩︎
Kumar, D., Chaturvedi, M.K., Sharma, S.K. and Asolekar, S.R., 2015. Sewage-fed aquaculture: a sustainable approach for wastewater treatment and reuse. Environmental monitoring and assessment, 187(10), pp.1-10. ↩︎ ↩︎ ↩︎
Lightfoot, C., Bimbao, M.A.P., Dalsgaard, J.P.T. and Pullin, R.S., 1993. Aquaculture and sustainability through integrated resources management. Outlook on Agriculture, 22(3), pp.143-150. ↩︎ ↩︎
Datta, S. (2006). Waste Water Management Through Aquaculture. Journal of Environmental Management. 1. 339-350. ↩︎
Mukherjee, J. (2020) citing Dhrubajyoti Ghosh. ↩︎
Prein, M. (1988, December). Wastewater-fed fish culture in Germany. In Edwards, P. and Pullin, RSV Wastewater-Fed Aquaculture. Proceedings of the Internation al Seminar on Wastewater reclamation and Reuse for Aquaculture, Calcut ta, India (pp. 6-9). ↩︎ ↩︎ ↩︎ ↩︎
One issue with the fish ponds in the German case was the high variability of the weather. Less sun in the Fall and Spring meant that algal production was much lower, in turn impacting fish growth and the ability of the system to treat wastewater at constant rates. In the winter months, ponds will often freeze, leading to oxygen deficiencies and fish deaths. As solar radiation can fluctuate throughout the day, the fish ponds require daily management to balance fish growth, algal growth, nutrient removal, and too much sewage that would lead to fish deaths. ↩︎
Calculated using the Indian Rupee to US Dollar exchange rate in 2000, adjusted by the author for inflation of USD in 2021 from data provided by Jana, B. B., Heeb, J., & Das, S. (2018). Ecosystem Resilient Driven Remediation for Safe and Sustainable Reuse of Municipal Wastewater. In Wastewater management through aquaculture (pp. 163-183). Springer, Singapore. ↩︎
In Israel, for example, mid-century kibbutzim colonies, which were often limited in the groundwater available to them, experimented in the 1960s with reusing sewage for fish production.In Egypt, the government has put its hope in wastewater-fed aquaculture, in an attempt to increase domestic protein production and maximize use of water. ³ ¹⁹ See also Kolkovsky, S., Hulata, G., Simon, Y., Segev, R., & Koren, A. (2003). Integration of agri-aquaculture systems the Israeli experience. In: Gooley, G. J., & Gavine, F. M. (Eds.), Integrated agri-aquaculture systems: a resource handbook for Australian industry development. Rural Industries Research and Development Corporation. ↩︎
El-Zohri, M., Hifney, A. F., Ramadan, T., & Abdel-Basset, R. (2014). Use of Sewage in Agriculture and Related Activities. In: Pessarakli, M. (Ed.), Handbook of plant and crop physiology. CRC Press. ↩︎ ↩︎ ↩︎
In Germany in the 20th century, consumers at first rejected these fish, but municipalities engaged in public communication campaigns to convince people otherwise. ¹⁵ In Lima, Peru, researchers conducted a study of whether the fish were accepted by consumers at the market, and were surprised to find out that people weren’t so bothered when they found out where the fish came from. ²¹ In Kolkata, too, sewage-fed fish still constitute 40% of the local fish market, even when consumers have alternatives available. ↩︎
WHO (2015) Sanitation. Fact sheet no. 392. World Health Organization, Geneva ↩︎ ↩︎
Cointreau, S. J. (1990). Aquaculture with treated wastewater: A status Report on studies conducted in Lima, Peru. Applied Research and Technology (WUDAT), Technical Note No. 3. The World Bank Water Supply and Urban Development Department: p. 1-56. ↩︎
In a fourth trial, only 6% were rated as “unacceptable”, but this was because they deliberately increased the ratio of sewage-to-water above the acceptable level, to mimic an “accident”. Still, these same fish were then rated as “very good” when the sewage level was decreased for a subsequent 30 days. This shows that even in the case of an accident, fish can easily recover to being safe for consumption. See UNEP International Environmental Technology Centre. (2002). Environmentally Sound Technologies for Wastewater and Stormwater Management: an International Source Book (Vol. 15). International Water Assn. ↩︎
Where there are insufficient resources to build sanitary requirements into the system, researchers recommend that cleaning, butchering, and packaging be done in sanitary conditions, so that fish muscle does not risk being contaminated with pathogens on the skin or in intestines. Cooking fish thoroughly is also recommended—and in Kolkata, local cuisine fortunately does not include raw fish. Another proposal is to transfer fish to clean water ponds two weeks before harvest; this both reduces the risk of pathogens being present in fish muscle and intestines, and helps to eliminate possible unpleasant odours. Edwards P. (1990) Reuse of human excreta in aquaculture: A state-of-the-art review. Draft Report. World Bank, Washington DC. And when it comes to the presence of toxic chemicals, there is also good evidence to show that this is not a significant problem. However, this does depend on local conditions. For example, people in industrialized countries use many more detergents and pharmaceuticals that may impact the fish. This includes a broad category of toxins called “emerging contaminants” which are found in new products like beauty products and certain pharmaceuticals. There have been little recent studies in industrialized countries on the effects of these products on sewage-fed fish—in large part because these systems had largely been phased out by the time these household commodities became more prevalent in the last fifty years. ³ ⁸ ¹¹ ¹⁹ ²⁹ ³⁰ ³² ↩︎
Edwards, P. (2004). Decline of wastewater-fed aquaculture in Hanoi. Aquaculture Asia, Volume IX (4, October-December): 13-14. ↩︎
Hoan, V. Q., & Edwards, P. (2005). Wastewater reuse through urban aquaculture in Hanoi, Vietnam: status and prospects. Urban aquaculture. CABI International, Wallingford, 103-117. ↩︎
Saigoneer (2019). Only 13% of Vietnam’s Urban Sewage Is Treated Before Discharge. The Saigoneer. https://www.saigoneer.com/saigon-environment/17571-only-13-of-vietnam-s-urban-sewage-is-treated-before-discharge ↩︎
Kiet, Anh. (2019). No technology can radically clean Hanoi’s polluted river if sewage not treated: Mayor. Hanoi News. http://hanoitimes.vn/no-technology-can-clean-hanois-heavily-polluted-river-if-people-keep-pouring-sewage-into-it-mayor-300420.html ↩︎
Bunting, S. W. (2007). Confronting the realities of wastewater aquaculture in peri-urban Kolkata with bioeconomic modelling. Water Research, 41(2), 499-505. ↩︎ ↩︎
Jana, B. B. (1998). Sewage-fed aquaculture: the Calcutta model. Ecological Engineering, 11(1-4), 73-85. ↩︎ ↩︎
Stein, S. (2019). Capital city: Gentrification and the real estate state. Verso Books. ↩︎
Mara, D. (2013). Domestic wastewater treatment in developing countries. Routledge. ↩︎ ↩︎