Sewer systems

Author: Nora Lewis

Suggested Citation:

Lewis, N. (2026). Sewer systems. Technology Assessment Project Case Study Library, University of Michigan. https://stpp.fordschool.umich.edu/tap-case-study-library/sewer-systems

Sewer Systems

Key Takeaways

• Technology like sewer systems can stabilize communities and curb public health and environmental disasters
• The economic, social, and political development of communities is hastened by these kinds of stabilizing technologies
• More localized governance of sewer systems or other public goods may increase local autonomy and help shape technology to local conditions and needs
• Still, proper worker's protections and effective stabilizing infrastructure are not a given in places with different regulatory challenges

London and the Modern Sewer System

Around the mid-19th century, the city of London was experiencing a severe public health crisis. Cholera and typhoid ran rampant among the population, and the city's poor waste infrastructure proved to be a key factor in this crisis. Old and simplistic "cesspits," or underground chambers where human waste could be temporarily deposited, were insufficient in sanitarily storing their contents but were used all across London (Jackson, 2014). These cesspits usually lacked the capacity to hold large amounts of waste, experiencing periodic leakages into groundwater supplies over the years. In 1848, the Metropolitan Commission of Sewers was established in order to oversee the modernization of London's sewer system once and for all (Jackson, 2014). Yet despite best efforts, the commission failed to minimize the city's contaminated water supply. They replaced cesspits with more localized drains that emptied into sewers, and then eventually drained into the Thames River. This practice made the body of water thick and dark with raw sewage, contributing further to disease-ridden water supplies and deeply unpleasant living conditions.

The grime of the Thames remained so dire that in 1858 Londoners deemed a period of two months "The Great Stink," as human and industrial waste boiled under the hot summer sun (Collinson, 2019). On the tails of several cholera outbreaks, government officials were motivated to re-think London's sewage systems after this "Great Stink," employing the guidance of British civil engineer Joseph Bazalgette. Bazalgette took an innovative approach to crafting new infrastructure, designing a set of oval sewage pipes that limited sludge deposition and prevented flooding or leakages (Latham, 1878). These pipes were slightly sloped, so as to transport waste effectively to outfalls, or waste deposit centers that dotted the city's outskirts. Pumping stations were strategically positioned along main sewer lines, allowing waste from more localized sources to be stewarded to these outfalls. Bazalgette's design essentially eliminated cholera outbreaks in London, an achievement that has saved thousands of lives and improved the livability of the city immensely (Collinson, 2019). Though wastewater management systems have existed in cultures across the globe for thousands of years, from the Indus Valley to Ancient Greece, Bazalgette's sewers represented a watershed moment in the context of unprecedented urbanization and modern population growth (Angelakis & Rose, 2014). His 19th-century infrastructure is still intact in modern London, though expanded upon and retrofitted for current use, acting as a crucial touchpoint for modern sewer systems around the world.

Minimizing Risk

In several key ways, Bazalgette's designs helped minimize risk for Londoners. Principally, the shift from cesspits to an organized sewer system minimized the rampant health risks posed by overflowing cesspits. Where these older devices tended to leak and require frequent maintenance, Bazalgette's sewers centralized waste and kept it flowing away from drinking water supplies and the Thames. This consolidation of waste into a contained network of pipes removed many of the risks associated with cesspit upkeep, such as exposure to leakages, harmful pathogens, and unpleasant smells (Collinson, 2019). By limiting how much people had to directly interact with waste, the risks of cholera and other water-borne diseases were effectively eliminated. From a public health standpoint, Bazalgette's innovation was crucial in minimizing the risks of disease that had once wreaked havoc on London's population.

The modern sewer system also minimized many of the risks that cesspit cleaners dealt with in their day to day life. Before 1858, cesspits were prone to producing toxic gas as a result of fermented human waste, fumes which often overpowered and sometimes instantly killed cesspit cleaners (The Victorian Web, 2009). Nightmen, as these cleaners were sometimes dubbed, usually cleaned and transported waste after midnight due to the "unsightliness" of their work (The Victorian Web, 2009). Waste had to be placed in buckets under the supervision of "holeman," who were lowered down into cesspits and filled buckets by hand. Then "tubmen" brought these buckets of waste back to a cart, where they would eventually be transported to dust yards or manure wharves for utilitarian use, or dumped into the Thames. The job was not just unpleasant for the smell, but also physically arduous and intensely stigmatized in Victorian society.

Poor regions of London also saw infrequent cesspit cleaning, if any at all, which meant that public health and quality of life risks were concentrated among the city's poor. Bazalgette's centralized sewer system minimized these class-based discrepancies in waste management, though wealthy enclaves saw more speedy connections to the new system than their less wealthy counterparts along the Thames (Science Museum, 2021). Still, waste management was no longer dependent on the labor of cesspit cleaners, who came from London's lowest class but were routed to wealthy neighborhoods as a first priority. The health risks that these workers used to incur were no longer present (at least in such a direct, unregulated way), and their home communities were no longer subject to suboptimal cleaning routines which heightened their risk of death and disease.

Where cesspits and cesspit cleaning posed immense risk to the health and wellbeing of London's populations, Bazalgette's streamlined sewers made day-to-day life decidedly less risky. Modern sewers stand as a successful example of technology that contained risk, and as a result stabilized populations.

Population Stabilization and Resilience in Modern London

Closely intertwined with the minimization of risk was this stabilization of populations. Dependable waste management systems shielded citizens from the shocks of cholera and typhoid that once plagued London every 10 years. Now, mass death resulting from contaminated water and overflowing cesspits did not periodically disrupt the lives of Londoners as it had in the past. The health of the Thames was also stabilized in the wake of modern sewers, as sewage was no longer directly routed to the central body of the river. Soil quality also benefited from new sewer technology, as waste leakages occurred more infrequently. Together, these environmental and quality of life improvements helped to stabilize the lives of London's residents.

This stabilization was integral to the population growth that London experienced between the 19th and 20th centuries. The city's population sat at roughly one million people in 1800, but grew to about seven million by the 1910s (Hitchcock, 2023). By 1860, right as Bazalgette's sewer designs began to take the city by storm, London was home to over three million inhabitants. The next decades of the 19th century saw the largest population growth in London's history, as modern sewer systems became fully integrated into the city's wastewater infrastructure (Hitchcock, 2023). By the numbers, population growth is curbed by high rates of mortality and low life expectancy, two symptoms of London's frequent cholera outbreaks. Though there are an array of advancements, ranging from public health and safety breakthroughs to changing migration patterns, that impacted London's growth during this time, it is likely that such a leap would be impossible without the stabilization provided by centralized sewers.

Large scale and resilient sewer infrastructure opened the door to urban life that didn't need to be constrained by the many perils of ineffective waste disposal. Because modernized sewers became so centralized in this period, it was also easier to scale-up operations over time and incorporate new lines into the pre-existing system. Bazalgette's designs were composed of five main brick-lined sewers that stretched along the north and south banks of the Thames. He ordered for the sewers' tunnels to be doubled in size from their original dimensions in order to accommodate the city's rampant population growth (Collinson, 2019). Still, London's population ballooned close to six million people at the time of Bazalgette's death in 1891, more than double the population when he first constructed plans for the sewers in the 1850s (Collinson, 2019).

The sewer infrastructure of Bazalgette's era is still in use today, although it's been expanded many times over. And while these designs have been fairly resilient considering their construction nearing 200 years, there are still problems posed in the context of modern population levels in London. Today, the city is home to about nine million people, and its sewer system has been weighed down by the waste of this hefty clientele. 39 million tons of sewage flows into the Thames every year, as the system is often overwhelmed with heavy rainfall and generates considerable runoff (Varghese, 2018). The health and environmental risks of this runoff are not novel, yet in the context of more intense rainfall in the wake of a warming planet, this problem seeks to worsen without intervention.

This intervention has come about in the form of a new "super" sewer, or the 16 mile-long Thames Tideway Tunnel, completed in March of 2024 (Fisher, 2024). The project cost five billion pounds to construct, and is meant to off-set raw sewage outflows into the Thames. The tunnel is able to store 600 Olympic-sized swimming pools of liquid before it is pumped into sewage treatment plants. Still, some have expressed concern over the project, positing that it's a band aid solution to the realities of climate change and population growth (Varghese, 2018).

London's Victorian wastewater system has been integral to supporting its population growth and role as an urban powerhouse, but continues to face uncertainty as rainfall intensifies and its infrastructure ages. In the meantime, its sewers are tested by populations outpacing Bazalgette's wildest dreams, and the health of the Thames suffers as a result.

Valuations of Waste Work

Professions in wastewater management look much different than they did in the days of 19th-century cesspit cleaners. While these individuals were historically from the lowest social class and faced highly hazardous conditions with little regulation or protective gear, wastewater management has seen several key shifts over the last 150 years. Today, an average sewer maintenance technician and sewer cleaner in London makes between £22,000 and £34,000 a year (Glassdoor, 2022). This role often does not require a university degree, though civil and wastewater engineers do, and see a heightened average pay of around £64,000 as a result (Economic Research Institute, 2024). Wastewater management professions are also subject to greater health and safety regulations today, with the uptake of personal protective gear (PPE) and stringent training procedures on handling machinery, toxic substances, and confined space entry in place. These regulations have helped make jobs in waste management safer, particularly when they function under the regulatory framework of city and state governments.

Still, in places outside cosmopolitan hubs such as London, there may be less regulatory framework set in place to protect sewage workers on the job. The International Labour Organization published an article from Shafique Massih last year, a sewer worker and chair of the Punjab Sanitation Workers Union living in Lahore, Pakistan (Massih, 2023). Massih recounts the lack of protective gear available for himself and his colleagues, as well as his concurrent health problems and stigmatized place in society due to his occupation. Massih's conditions are mirrored in many places around the world, and highlight how though strides have been made in how we value and protect waste workers, there are persistent disparities in worker's protections and stigmatization.

When thinking about safety regulations in the sewage industry, there are also broader questions of centralization and decentralization to consider. In traditional collective sewer systems, oversight generally falls to city governments and municipalities. These government bodies are usually required to have safety protocols, workers' protections, and quality control guidelines in place for operations falling under their purview. When wastewater management becomes more decentralized, for example through individualized wastewater systems that may not fall under the governance of local or state authorities, safety protocols can potentially face erosion in the face of more heterogeneous regulations. Though there are certainly benefits to decentralized systems of waste management, there are also challenges that arise when potentially hazardous professions are vulnerable to corner-cut worker protections.

Collective and Clustered Management of Wastewater

Beyond traditional sewage systems, individual wastewater management represents an alternative to centralized sewers. Where collective wastewater management pools waste from many different sewage sources into one centralized system, individual or "clustered" wastewater systems treat sewage much closer to the source of generation. These clustered systems often cater to individual properties or communities, and serve over one in five households in the U.S. (EPA-OWM, 2012). Though clustered systems can operate in many different ways, they tend to include an underground septic tank and absorption field, where solids and grease not captured in a tank percolates into soil for purification (EPA, 2025). The soil must be sufficiently permeable for purification to occur. If not permeable enough, wastewater may accumulate at the surface of the field and pose health risks to nearby inhabitants, and if too permeable, there is a risk of improper purification and potentially contaminated groundwater supplies.

Clustered wastewater systems tend to be located in less densely populated rural and suburban areas that may not be supported by connections to broader waste systems. One of the central appeals of this kind of wastewater management is that systems can be more closely catered to the specific conditions of a community in terms of soil type, sloping, geology, and hydrology (EPA-OWM, 2012). While centralized systems of wastewater management are often built to accommodate large populations under one design, clustered alternatives can respond to the unique challenges facing a community through well-planned system designs.

Some find the autonomy granted by individual and community wastewater management to be empowering as well (EPA-OWM, 2012). Particularly in communities that have suffered from frequent sewage leakages, unfavorable geological or hydrological conditions, and contaminated water supplies, smaller means of waste governance have the potential to bring more stakeholders to the table when approaching these problems. One EPA report from 2012 highlights 14 different communities that have adopted effective community wastewater management systems (EPA-OWM, 2012). These projects vary in context and complexity, almost always employing some kind of financial and managerial assistance from local public health and environmental authorities. Some use more resources than others, with places like Fairfax County, VA choosing to emphasize individual wastewater system maintenance reminders among homeowners rather than complex compliance and ownership mechanisms (EPA-OWM, 2012). Other communities, such as Phelps County, MO have adopted programs where local water supply districts are given full ownership of wastewater systems, managing eight clustered systems instead of hundreds of individual septic systems for more affordable service (EPA-OWM, 2012).

Though not all these clustered systems employ cutting-edge technology, newer systems have the potential to undercut traditional centralized systems on technical prowess. Tools such as advanced pumps, float switches, and even databases to track regulation compliance and water quality among decentralized systems have helped community-led management projects maintain quality control (EPA-OWM, 2012). With rising concerns of climate change-related weather shifts, communities battling intensifying floods and rainfall can be better equipped against sewage overflows with more precise management systems at their disposal. Still, the effectiveness of such technology can be heavily dependent on funding and access to high quality environmental assessments and engineering expertise. Case studies highlighted in the aforementioned EPA report all had some kind of stakeholder engagement process set in place, receiving guidance and financial support through local and state agencies who recognized a need for waste management alternatives. If communities have these support systems set in place, or are empowered to ask for such support, then clustered systems can be a path toward more autonomous and tailor-made waste management systems.

Relevance to Advanced Nuclear Energy

We chose sewers as a key example of a stabilizing technology. We found that the design and distribution of sewer systems helped save millions of lives and support greater population growth and more dispersed human development. It's clear that the politics around sewers are much less divisive than those around nuclear energy, yet both energy and sanitation infrastructure has proven key for stabilizing life. More decentralized systems of sewage management, such as clustered systems discussed below, have been adopted in rural communities with less access to centralized and traditional sewage infrastructure. In these cases, the clustered systems have allowed for more locally-tailored sewage management, which may take local ecological conditions and community needs into account. Thinking of advanced nuclear, this may act as an example of smaller, more decentralized tech giving rural communities greater energy autonomy.

Appendix: Where do Sewer and Nuclear Energy Technology Diverge?

Sewer systems and nuclear energy are two technological realms that deal with the question of centralization. In the context of sewers, the aforementioned clustered systems promote waste management that can function effectively without the infrastructure of traditional sewer systems. Here, waste management is individualized and customizable, affording households the same ability to dispose of their waste as those connected to centralized systems.

When thinking of present-day nuclear energy technology such as SMRs, there is also a similar appeal to "in-your-backyard autonomy." Yet what makes SMRs distinct from clustered waste systems is that the latter functions within a very different context of "public good." There is a general consensus that managing our sewage is central to maintaining livable and healthy lifestyles. Waste management systems are a public good that you'd be hard-pressed to find many in opposition to. Yet the context of nuclear energy tech like SMRs is laden with a much more complicated idea of how we can generate energy to contribute to this public good. With roots in militarism (and visions of explosions and toxic meltdowns coming to mind for many), nuclear reactors exist in a more complex context. Having a reactor in your backyard may not be quite as palatable to the general public as a septic tank.

Given these different contexts and levels of complexity, the ability for sewers and nuclear tech to be decentralized varies. The detailed mechanisms of wastewater management systems might not be obvious to the average homeowner, but the need for a septic tank is fairly simple to grasp. Maintenance of such systems does require expertise, but this expertise is generally not as heavily regulated as that of nuclear energy. SMRs on the other hand are an incredibly complex technology that fall under the strict guidelines of bodies such as the NRC, requiring not just expertise to maintain but also considerable federal oversight. Thus, models of community ownership and decentralized governance of technology look different when examining sewage management and nuclear energy generation.

The insular nature of nuclear expertise seeks to box out community members from a seat at the table within decentralized systems of governance. Sure, we might all recognize the need to produce energy for our survival, but is there any broad consensus that generating this energy via a "reactor in your backyard" is the most appealing path forward? Not likely (or not yet, at least). Nuclear energy systems are perhaps a more daunting task to fully comprehend compared to their sewage counterparts, which can greatly hinder the effectiveness of meaningful community engagement in the governance process. So while clustered wastewater management systems and SMR technology may both seek to deliver a public good in a more individual form, there exists a vast disparity in how this community governance can take root.

Key Sources

Collinson, A. (2019, March 26). How Bazalgette built London's first super sewer. Museum of London.

Environmental Protection Agency. (2018, November 15). Types of septic systems.

Environmental Protection Agency, Office of Wastewater Management. (2012). Case studies of individual and clustered (decentralized) wastewater management programs. Environmental Protection Agency.

References

Angelakis, A. N., & Rose, J. B. (2014). Evolution of sanitation and wastewater technologies through the centuries. Vol. 13. IWA Publishing.

Collinson, A. (2019, March 26). How Bazalgette built London's first super sewer. Museum of London.

Economic Research Institute. (2024). Wastewater engineer salary in London, United Kingdom.

Environmental Protection Agency. (2025, May 20). Types of septic systems.

Environmental Protection Agency, Office of Wastewater Management. (2012). Case studies of individual and clustered (decentralized) wastewater management programs. Environmental Protection Agency.

Fisher, J. (2024, March 27). Thames Tideway Tunnel super sewer completed. BBC.

Glassdoor. (2024, April 29). Salary: Sewer technician in United Kingdom 2024.

Hitchcock, T. (2023). A population history of London. The Proceedings of the Old Bailey.

Jackson, L. (2014, November 19). Cesspools and sewers: Toilets in dirty old London. Yale University Press.

Latham, B. (1878). Sanitary engineering: A guide to the construction of works of sewerage and house drainage, with tables for facilitating the calculations of the engineer. E. & F.N. Spon.

Massih, S. (2023, April 27). As a sewer worker, I want respect and safer working conditions. ILO Voices.

Science Museum. (2021, February 2). Flushed away: Sewers through history.

The Victorian Web. (2009, February 4). London nightmen.

Varghese, S. (2018, December 8). London's super sewer won't solve the city's epic poop problem. Wired.

Photo: Sewage pipes under London, 19th century. Wellcome Collection / CC BY 4.0, via Wikimedia Commons