Cesspits and Drywells Are Advanced Technology… for the 16th Century
Cesspits and drywells are ancient technologies but they are still used today in some locations. In general, they are an outdated and unsafe method for dealing with septic waste. Concerns about human health and environmental quality has meant that cesspits and drywells are no longer employed for septic use in most areas of North America, and existing ones will eventually need to be replaced with modern on-site septic treatment systems.
Basically, A Hole in the Ground
The term “cesspit” (or “cesspool,” “cesstank,” “soak pit,” depending on where you live) can have various meanings, but these all refer to a structured hole in the ground. The hole is typically lined with stone, brick or concrete and is designed to receive household and human waste.
A cesspit can be an unsealed, porous tank or well-like structure that retains solids but allows liquids to drain freely into the surrounding ground. It can be a sealed tank that allows liquid to drain off into a drywell. A modern cesspit can be as simple as a sealed, vented holding tank.
The main feature of a cesspit is that it is designed to hold waste, not to treat it. Cesspits, even the porous type that allow liquid to seep out, require periodic, often frequent, cleaning. It’s a method of dealing with human waste and household sewage that dates back centuries.
Cesspits function on the same idea as a privy or outhouse, expanded a little to accommodate household wastewater and connected to indoor plumbing. As far as holes in the ground go, well… nasty.
Technically, a drywell is a bit different than a cesspit. When you hear the word “well” you think of water. A drywell, then, is not a source of drinking water, but a structure designed to collect and hold wastewater, allowing it to passively soak back into the ground.
Drywells are related to the French drains commonly found in basements, and the landscaping features known variously as retention ponds or catchment basins. All of these structures are designed to manage the flow, movement and storage of excess water, whether it’s stormwater, normal water seepage or wastewater. A drywell can be quite deep to accommodate sufficient water volume.
Some people use “cesspit” and “drywell” interchangeably, perhaps because they both function as receptacles. The key point to keep in mind, however, is that neither is designed to treat waste. Instead of a stinking pile of waste laying on the ground, waste is dropped into a hole in the ground: out of sight; out of mind.
It’s Rudimentary Waste Management
When we talk about septic systems, we have the catch-all term “on-site waste treatment systems” to refer to the full range of waste treatment needs and related technologies for residential and commercial buildings.
Remember, septic tanks are designed to encourage the separation and decomposition of solid waste. A leaching field treats septic effluent by controlling the flow of effluent, by the separation between groundwater and where the effluent enters the soil (typically a metre or more), and by exposure of the effluent to soil microbes and vegetation that degrade or take up pathogens, nutrients and organic material.
Cesspits and drywells are a different beast altogether, because they do not take any of these treatment design features into consideration. They are not designed or used for treating household or human waste. They are best thought of as “on-site waste management systems,” because they only store the solids, and maybe let the liquids seep back into the ground.
Therefore, waste ultimately has to be physically removed from the cesspits and drywells, and untreated waste and effluent easily enters the environment, posing a threat to human health and the environmental quality.
A rudimentary system consisting of a cesspit attached to a drywell looks something like a septic system. Here, the cesspit collects the waste and the effluent eventually flows into the dry well, to seep back into the ground. The difference is that the drywell does not distribute the effluent in a way that allows soil to act as a treatment mechanism.
Cesspits and dry wells simply keep waste in one out-of sight place as it soaks untreated into the soil.
Of Night-Soil and Gong Famers
We remember the ancient Romans with admiration for developing plumbing and sewer systems. Historically, cesspits were also a very common way of dealing with household waste in populated areas, and they were not necessarily a less developed technology.
Archaeological research being done in the Dutch city of Leiden gives a really interesting window on cesspits as an important part of a medieval city’s infrastructure . Most buildings at that time incorporated cesspits as collection points for “night soil,” that is, human waste.
However, 16th century cesspits were not simply festering pits of poop in tenement basements. They were regularly cleaned (as often as weekly) by “night-men.” Cesspit cleaning was a tightly regulated city service.
The cleaning was done at night to limit the impact of odors on daily life. Night-men used shovels to transfer the waste to large tubs, which they then carried to barges to be transported away from the city.
Night-men had to be quiet, careful and neat. Spillage was not tolerated, and resulted in summary termination of sloppy night-men! Overseers checked to make sure the cesspits were thoroughly cleaned out, and kept careful records of the services provided.
Cesspit infrastructure and management was not limited to Holland, though; it was widespread in Europe and other populated parts of the world. In the UK, cesspit cleaners were known as “gong farmers,” gong being the term for the privy as well as its contents.
The collected human waste was actually a resource: it was valued as a fertilizer.
Cesspit systems kept early cities and the local environment pretty clean. When sewers eventually replaced the cesspits, they carried raw sewage directly to nearby canals and rivers, which made them the stinking, polluted waterways we typically associate with the historical city environment.
Blame the landlords: installing sewers was in the long run cheaper than building and maintaining individual cesspits in each building and employing all those night-men and gong-farmers.
Out of Sight Is Not Out of Mind
Maybe it’s because we walk upright on two feet and so we live our lives several feet above the ground, but most of us tend not to think too much about what’s underground. Humans have a long history of burying things that we need to get rid of.
Landfills are an obvious example, and in the modern era we’ve also thought that burying hazardous chemical waste might be a good idea. Again, out of sight, out of mind. Until it’s not.
The Love Canal in upstate New York, USA, was used to bury thousands of barrels of toxic chemicals. The land was eventually developed for housing. Several years on, the barrels began to rupture, the chemicals seeped into the ground and people began to get sick as the chemicals leaked into their basements. Unfortunately, similar stories can be told for many industrialized areas.
Human waste is also hazardous to human health and the environment when, like industrial chemicals, it is released without treatment into the environment.
A modern septic system uses installed components and site features like soil and vegetation to separate and decompose solids, and to further treat liquid effluent to remove pathogens, organic material and nutrients.
A cesspit doesn’t accomplish any kind of treatment. The focus is simply on holding waste until it can be removed for later treatment and safe handling at some other location.
In this way, cesspits function on the same idea as pit latrines or portable toilets (“Porta Potty” and the like). They isolate human waste in a contained space to facilitate collection and reduce odors.
The sanitary isolation of human waste is an age-old problem wherever people congregate or stay in one place for extended periods of time.
Even in “wild” places like Mt Rainier, handling human waste is a critical issue. Mt. Rainier is a highly popular hiking destination, but the environment is too severe for restroom facilities. Here, the National Park Service mandates that hikers carry out all waste, including human excrement. (They provide convenient blue bags for this.)
Waste Disposal is Not Waste Treatment
In the best case, a modern cesspit is a sealed, impervious structure that holds and isolates household waste from the environment. While regular and frequent pumping is expensive and less than ideal, the waste does not pose a risk to human health or the environment.
In the worst case, a cesspit is a permeable, stone, brick or concrete hole that allows waste to seep into the ground. It then becomes a dangerous source of environmental pollution and a human health risk.
In many instances, permeable cesspits or drywells were deliberately dug deep enough to penetrate the water table, with the intention of having groundwater flow distribute the liquid waste. This “dilution is the answer to pollution” is an old way of thinking. It has only resulted in contaminated aquifers.
A carefully designed septic system maintains a suitable separation between where waste effluent enters the soil and the saturated soil zone. This ensures that there is sufficient capacity in the vegetative and aerobic, microbially active regions of soil to treat the effluent before it joins with groundwater.
With a cesspit or drywell, the volume and flow of waste and effluent is uncontrolled and feeds directly to anaerobic, microbially inactive regions of the soil. The result is that waste remains untreated as it enters water supplies.
Improper sizing of cesspits and drywells also have often left them susceptible to becoming plugged with solids and to household backups.
The differences between septic systems and cesspits or drywells are dramatic. A septic system controls the movement, flow and placement of household waste and its effluent to maximize on-site treatment. A cesspit and drywell are uncontrolled conduits through which untreated sewage enters and pollutes the environment.
Untreated Waste is Hazardous
Untreated household waste can contain harmful pathogens (bacteria, viruses, parasites and other microorganisms) that can contaminate the surrounding soil and groundwater eventually entering and contaminating surface water.
When surface water or groundwater are sources of household water for drinking, cooking and bathing, people are then exposed to pathogens. Waterborne disease is a common problem around the world and one of the most frequent causes of human illness.
Typhoid, cholera, dysentery and hepatitis are just a few of the many types of waterborne diseases associated with the lack of proper sanitation to deal with human waste.
People can also be sickened by exposure to contaminated soil near cesspits and drywells.
Water contamination is a particular concern for those who get their water from private wells, because unlike public water supplies they are not routinely tested for the presence of pathogens or harmful chemicals (household chemicals, for example, or nitrates).
Untreated household waste is also a source of excessive nutrients such as nitrogen and phosphorous. These and other nutrients negatively impact the environment by causing eutrophication of surface water. Eutrophication of surface water compromises the habitat for fish and other aquatic life as well as its acceptability for human use (e.g., swimming, boating, fishing, etc.)
Septic systems and sewage systems are based on the containment, transport and treatment of household wastewater. Cesspits and drywells are based on getting wastewater out of sight and hoping for the best.
The Lingering Hazard of Cesspits and Drywells
Hopefully, I’ve impressed upon you that cesspits and drywells are serious pollution hazards. Even when they are no longer used, perhaps having been replaced by a modern septic system, they remain as a source of water pollution for years after.
Beyond pollution, abandoned cesspits and drywells are lingering hazards in much more dramatic and disturbing ways.
Often, over the course of time, vegetation overgrowth can conceal their precise location. Or, poor or non-existent record-keeping over the course of property transfers can mean that even a well-manicured suburban lawn can conceal an underground structure.
When old waste eventually drains out of the structure, the interior walls are no longer supported and can collapse, forming a sinkhole. People have fallen into these sinkholes and have even died after being overcome by noxious gases or by drowning.
Cesspits and drywells are old technology. The typical age of these structures, coupled with old building techniques and materials, and the ease with which old, underground structures can become invisible, makes them even more than just a pollution hazard.
So, It’s Time to Clean Up the Cesspit Mess!
When cesspits are evaluated under modern standards, they virtually always come up deficient. They were commonly placed without consideration of soil structure, vertical separation from the water table, capacity, flow acceptance or structural resiliency (those collapsing pits we saw above).
Self-contained plastic cesspits are still used in some parts of Europe, particularly where site conditions limit the installation of a septic system.
In North America, regulations vary by country and province or state. While installation of new cesspits or drywells for wastewater containing human waste is generally banned, there are varying accommodations for existing structures.
Some are “grandfathered” into property transfers to allow their continued use, while in other jurisdictions a property transfer compels an upgrade to a septic system that meets current standards.
British Columbia regulations get right down to business concerning cesspools, in the Sanitary Regulations of the Health Act:
All privy closets, privy pits or vaults, cesstanks or cesspools now in use are hereby declared nuisances, and the same shall be thoroughly emptied, cleaned and disinfected and filled with clean earth. [en. B.C. Reg 243/68.]
The writers of the Health Act put it mildly: cesspits and drywells, when used for receptacles of human waste, are a nuisance. They are a significant source of pollution and a lingering human hazard for as long as they remain in the ground.
Wherever they exist, the safe course of action, for the health and safety of those living on the property and for the health of the environment, is to remediate existing structures and replace them with a properly designed and installed on-site treatment system.