History of Sewers

Cesspools and Cholera: The Development of the Modern Sewer

by Joaquin I. Uy

This is an excerpt of an article in Dam Nation: Dispatches from the Water Underground.

Ancient PlumbingAncient PlumbingImagine walking through one of the many fast-growing cities of Europe during the sixteenth century. See the open-air markets filled with the noise of bartering merchants and horse-drawn carts. Smell the aromas of fresh-baked bread, freshly picked vegetables -- and the stench of the nearby open cesspools, the gold standard of sewer systems in those days. Walk a little farther past the market into the town square. Watch your step, however: you'll be walking right next to shallow roadside trenches filled with human excreta flowing to the cesspools near the market. Still, don't pay too much attention to these open rivers of putrescence. You have to watch out for the occasional mixture of human waste and water that can come flying out of the second story of any house in the city. These were the customs of the day. Sewer systems were a lot more noticeable back in the good old days.
 

Today, all you're likely to see of sewers are the occasional street manholes and curbside steel gratings beneath which giant crocodiles and mutant turtles are imagined to dwell. The story of our sewers is a turbulent, mixed-up history of bad decision after bad decision that has brought us to a horrible relationship between ourselves and our wastes. Our story begins even before the smells of marketplace and open-air sewer mingled in the metropolises of renaissance Europe.
 

Ancient Pipes

During the latest U.S. invasion of Iraq, the streets of Baghdad ran with raw sewage, thanks to bombs that targeted sewer infrastructure. Fifty miles to the north, the ruins of the ancient city of Eshnunna contain brick sewers connected to water-flushed latrines, embodying the essential principles of modern sewage treatment -- in 2500 BC. Even more sophisticated sewers in the Indus Valley featured brick-lined pits similar to modern septic tanks and enclosed drains that carried both sewage and stormwater out of the ancient city of Mohenjo Daro. The Minoans built latrines connected with vertical chutes to an elaborate stone sewer system. The Persians, Athenians, Macedonians, and Greeks also built impressive sewer systems.

The Romans integrated earlier sewer innovations into the cloaca maxima, first built around 800 BC. These open drains were designed to carry stormwater, but the rains also flushed away piles of excrement and household rubbish thrown into the streets. During storms, these ditches were sources of a horribly revolting stench. Ancient Roman sewer designers also developed cesspools, forerunners of modern-day septic tanks. Sewage first flowed into a large stone or concrete tank where heavy solids settled to the bottom and lighter particles floated to the top. The partially cleaned liquid flowed into a nearby body of water. Collected sludge was either used as fertilizer or simply buried.

After the fall of the Roman Empire, Christianity had a monopoly on truth and reality. It was unholy to be clean. "During the so-called Dark Ages, there arose a brotherhood among men noted for skill in combat," notes Jon Schladweiler, historian of the Arizona Water & Pollution Control Association. "There also evolved a creed that uncleanliness was next to godliness. As such, bathing and sanitation became quite uncommon; homes, towns, and streams became filthy." In some cities the Roman aqueducts and cesspools were maintained, but most fell into decline resulting in a return to the open drainage ditches. Urine and feces remained devalued and worthless.

In medieval European cities, chamber pots were emptied directly into the streets. New fashions and courtesies evolved -- gentlemen wore high heels to protect their long trousers from the filth and broad brimmed hats to protect their heads from excrement flying out second-story windows. Ladies walked close to the buildings, where they were less likely to receive a direct hit.

Diseases spread across Europe. Between a quarter and a third of the population died from cholera, typhoid fever -- spread by excrement-contaminated drinking water -- and plague, which was transmitted by fleas living on rats who thrived in the filthy conditions. Dysentery alone wiped out ten thousand crusading knights and foot soldiers. During the Crusades, Europeans learned basic aspects of science and hygiene from the Muslims whose culture they sought to destroy, and plumbing was rediscovered and brought back into use. But the open sewers remained open and caused huge problems in Europe's fast-growing cities.

In London, storm drain effluent poured into the Thames, which caused the years of 1858 and 1859 to be known as the Great Stink. Dr. William Budd commented on the historic nature of the event:

For the first time in the history of man, the sewage of nearly 3 millions of people had been brought to seethe and ferment under a burning sun, in one vast open cloaca lying in their midst. . . . Stench so foul we may believe had never before ascended to pollute this lower air; never before, at least, had a stink risen to the height of an historic event.

Scenes like this were common in other European cities and in the U.S. It wasn't until the mid-nineteenth century that scientists figured out disease was spread through contaminated water. The English, busy inventing their version of the flush toilet, started boiling their water. It was not long before Americans began inventing hundreds of different designs and models of water-flush toilets, and brought sewer technicians over from Europe to design sewer systems for their growing cities. In the U.S., the first waterworks was installed in Philadelphia in 1802. Construction continued steadily until, by 1880, 598 cities piped water to their citizens. With piped water, per-capita use increased from three to five gallons per person per day to 30 to 50 gallons per person per day.

All water piped into houses also had to be piped out. This meant that the cesspools overflowed regularly, spilling raw sewage into the streets. Engineers decided to connect the cesspools to the crude open-air sewers and the result was an increase in water-borne diseases such as cholera. People still didn't fully understand the relationship between disease and contaminated water. They drank from wells contaminated by outhouses leaching into the water table and from contaminated rivers and streams. Officials resorted to prayer as their citizens woke up healthy and were buried by nightfall.

City engineers eventually decided to design closed sewer systems, still using water as the vehicle to transport excreta. Then a debate occurred between the engineer masterminds of the day. Some wanted to return sewage to agricultural land. Others, arguing that "water purifies itself," wanted to pipe sewage straight into lakes, rivers, and oceans. By 1910, the debate was over. Sewage was being dumped into bodies of water on a grand scale, and cholera abated. Then, in the tradition of trading one problem for another, cities downstream of dumped waste started experiencing epidemics of typhoid when they piped sewage-laced water to the homes of their citizens. Thus began yet another debate: treat sewage before dumping it into rivers or filter the river water before drinking? Public health officials favored treating sewage before dumping it, and sanitary engineers favored dumping the sewage unfiltered and filtering water before drinking. The engineers prevailed, and as cities began to filter and disinfect their drinking water, typhoid also disappeared.
 

The Dawn of Centralized Sewage Systems

"Urban man today still unnecessarily pollutes streams, bathing beaches, bays and estuaries, without benefit of the excuse of ignorance which was available to his ancestors."

Harold Farnsworth Gray, "Sewerage in Ancient and Mediaeval Times", Sewage Works Journal, 1940

Imagine visiting bustling San Francisco at the dawn of the twentieth century. You walk down towards the wharves and can smell the bay long before you see the marshes, which have become festering pits of sewage. Smells like we're back in the Middle Ages. As cities grew, health officials realized that transporting sewage beyond the city limits was not enough and began building sewage treatment plants. As these systems evolved, engineers developed a two-tiered process comprising primary and secondary treatment.

Until the passage of the Clean Water Act in 1972, most cities only performed primary treatment, which mechanically screens out the trash and debris that float in sewage, then settles out the solid sludge. The resulting effluent was sent into a nearby watercourse.

Secondary treatment was developed to remove the polluting organic materials and nutrients that damage rivers and estuaries. This damage occurs when aquatic microorganisms proliferate in the glut of nitrates and phosphates in sewer effluent. When they die, their decomposition robs the water of oxygen, sometimes creating lethal "dead zones."

Wastewater plants also chlorinate treated wastewater in a last-ditch attempt to kill off any surviving bacteria. The new treatment plants' pumps, digesters, clarifiers, and conveyor belts consume massive amounts of energy, and are therefore very expensive to operate.

Billions of dollars later, upgraded and expanded plants employ sewage treatment methods that combine nutrients and toxins, creating a new by-product to be disposed of: sludge -- 1.6 billion dry pounds of it in the U.S. every year. Sludge is the de-watered, sticky black cake created by the truckload in modern sewage treatment plants. It consists of the indigestible solid remnants of everything that goes down household and industrial drains, including any number of the seventy thousand different chemicals produced in commercial quantities in the U.S.
 

Civilization Without Sludge

In her seminal essay Civilization and Sludge, sewage reformer Abby Rockefeller rails against the modern sewage system. No society in the world today deals well with human excreta. At all levels of technical sophistication, damage is done to water, soil, and human health -- whether by the pit latrine, the flush toilet, the septic tank/leach field, or, most insidiously and destructively, by the central sewage collection and treatment plant, which creates an unpredictably toxic, and therefore unrecyclable, sludge.

Rockefeller finds the economic and ecological costs of centralized sewer systems unacceptable:

Using water as a transportation medium for waste materials is the fundamental mistake that gave rise to so destructive and unfixable a sequence of mistaken technologies: sewers leading to vast water pollution; vast water pollution leading to sewage treatment; sewage treatment leading to the production of an unusable mix of all the pollutants that treatment could remove -- sludge, the climax inherent in sewers and the water carriage of wastes. The spending of resources -- time, energy, materials, money -- on upgrading the level of wastewater treatment, on the construction of sewerage, or on efforts to "clean up" sludge, can be no more than a waste of all those resources.

It is time to rethink centralized water sewage treatment systems. Imagine what our sewers might look like today if back in the early twentieth century we had taken a stand against dumping sewage into our lakes and rivers. Instead of constructing costly and convoluted processing systems to make such dumping "acceptable," we might have taken a more straightforward path. What if we'd decided people in Asia were on to something with the idea that our feces was beneficial? Or worked to develop innovative ways to kill all the bacteria, viruses, and other pathogens in our wastes while preserving the large amount of nutrients that plants love? We might have developed toilets that recycle waste and harness its potential energy, rather than depositing it on a waterslide down to a treatment plant.

Instead of a car in every garage and a chicken in every pot, we could strive for gardens in every house and neighborhood fueled in part by our own excreta! No matter what the alternative universe of sewage may look like, it is crucial that we dare to imagine this future for ourselves and for our children. Three conditions are necessary if we're going to save ourselves from our own shit. First, sewer avoidance: get off those awful centralized sewer systems, and if you're not on them, don't hook up! Second, waste recycling: promote low-cost, on-site technologies like composting toilets. Finally, the most fundamental change: we need to view our own excreta, without shame or disgust, as a rich and beneficial source of nutrients.