Why Cities Are Starting to Shun Sewers

Why Cities Are Starting to Shun Sewers

By Alia Dharssi

A worker services a toilet built by Sanergy, a social enterprise that builds container-based toilets in informal settlements in Nairobi, where sewers adequately service only 12 percent of the population.
SourceMukuru Kwa Reuben, courtesy of Sanergy


Because we need to change how we deal with our sh*t.

By Alia Dharssi

On the outskirts of Bangalore, India’s tech capital, an office doubles as a museum of the toilet. An exhibit in one room traces the history of sanitation, from ancient Mesopotamian sewers to Europe’s first flush toilets and the modern sewer systems built to process the waste they spurt out. Then, another exhibit turns to the global sanitation crisis — including a sculpture of naked babies representing the half-million children under 5 who die from diarrhea annually — and technologies to tackle it.

CDD Society, the nonprofit housing the display, wants Indians to think outside the sewer. It has built India’s first citywide fecal sludge treatment plant, which turns human excreta into compost with no electricity and no connection to an underground sewer. Built in 2015 at a capital cost of $94,000 (Rs. 6 million), it serves a municipality of 30,000 on the outskirts of Bangalore. But it is also increasingly emerging as a model for other Indian cities — which dump 70 percent of urban sewage untreated into the environment. More than a dozen cities, including three so far in 2018, have commissioned similar projects from CDD.

It’s not necessary to always have a pipe.

Sasanka Velidandla, CEO of sanitation nonprofit CDD

The organization and India are only part of a growing trend across multiple developing countries, where governments, entrepreneurs and nonprofits are eschewing Western-style sewer systems that use vast piped networks to deliver waste to centralized treatment plants. Instead, they are opting for decentralized approaches to treating poo and pee. Their models rely on trucks to transport waste to systems like septic tanks and latrine pits that use less water than sewers and recycle human waste. They are pitching themselves as the answer to the global sanitation crisis: 2.5 billion people, a third of the world’s population, lack access to a toilet, while an estimated 80 percent of human waste worldwide goes untreated.

“Infrastructure is being looked at from a different lens, which is to say that it’s not necessary to always have a pipe,” says Sasanka Velidandla, chief executive officer of CDD. “Sh*t can move on trucks.”


Almost 10,000 miles away from Bangalore, in Haiti’s Cap-Haïtien and Port-au-Prince, trucks pass by public toilets and homes serviced by SOIL, a nonprofit that provides toilets to the poor in Haiti. The trucks pick up and replace cartridges that collect their waste in container-based toilets. Then they deliver it to a wastewater treatment plant where it becomes fertilizer. “We’re on the cusp of a big change in the way we look at sanitation systems for the future,” says Sasha Kramer, executive director and co-founder of SOIL.

compost in action in a garden in port au prince

Everne Lafalaise, logistics coordinator for SOIL’s Port-au-Prince office, tends to seedlings growing in compost produced by SOIL in October 2013.

Source Courtesy of SOIL

Globally, more than 1 billion people live in slums with inadequate or no toilets. That condition is spawning a health crisis, with research linking poor sanitation to the transmission of diseases like cholera, malnutrition and intestinal worms. Less than 10 percent of wastewater is treated in some countries such as Lebanon and Cambodia, according to a 2017 United Nations report. But modern sewer systems, which cost millions to build and maintain, in addition to devouring water and electricity, are out of reach for many developing countries. More and more, countries and communities are seeking alternatives.

The U.N.’s Sustainable Development Goal on clean water and sanitation, which calls for universal access to toilets and decreasing untreated wastewater worldwide, is in some ways forcing nations to look beyond Western sewage systems, says Alyse Schrecongost, urban sanitation specialist at the Gates Foundation. “You can’t even pretend that your country is going to get there with sewers.”

conducting test on the composting process at soil's waste treatment facilities in northern haiti, vic hinterlang

A worker conducts a test during the composting process at SOIL’s waste treatment facility in Northern Haiti.

Source Vic Hinterlang, courtesy of SOIL

Even so, many see sewers as the “proper” way to provide sanitation, according to World Bank research. Policymakers often view the management of fecal sludge, which refers to human excreta gathered in on-site sanitation systems, as a stop-gap solution, leaving it to an unregulated private sector that dumps much of it in the environment.

But attitudes are changing. In 2017, India, Bangladesh and Zambia joined a growing number of countries with national policies on fecal sludge. Social enterprises, such as Sanergy in Nairobi and X-Runner in Lima, gather waste from dry, container-based toilets in urban slums before turning it into products like fertilizer, animal feed, compost and biogas. In Durban, public utilities are building decentralized wastewater plants to treat waste close to the source instead of expanding existing sewerage networks.

“We may, in the end, get rid of the large sewer systems,” says Tove Larsen, professor of urban water management at the Swiss Federal Institute of Aquatic Science and Technology, noting that the transition could be pushed by water scarcity in the face of climate change. Larsen leads a team researching ways in which a building housing apartments or offices can clean and reuse wastewater, including from toilets, showers and washing machines, on its own. But she says she expects China, India and Latin America to lead a global shift because they offer “huge” markets for decentralized wastewater treatment.


Workers perform maintenance at the fecal sludge treatment plant in Devanahalli, a growing municipality on the outskirts of Bangalore and the site of India’s first city-wide fecal sludge treatment plant.

Source Alia Dharssi

But decentralization is about more than saving money and the environment. It’s also about looking at human waste as a resource instead of something to be thrown away. Kramer established SOIL after visiting Haiti in the mid-2000s as a human rights observer. She heard stories about children dying from diarrhea — and about the decline of local agriculture and soil fertility. Providing clean toilets and turning the poop they gathered into fertilizer was a logical — and cost-effective — way to tackle both problems, she recalls.

On the other side of the world, a core part of CDD Society’s mission is to transform how people look at their waste. “There is still a huge gap in the outlook toward waste, both solid and liquid, as a resource,” explains Avinash Yadav Kumar, an urban planner at CDD. It will take multiple successful demonstrations of these alternative technologies to convince more people, he suggests. And that will take time. CDD, SOIL and others aren’t waiting though. The CDD plant in Bangalore takes sludge from trucks, cleans it with a gravity-based filter and turns it into compost.

Here, the future is clean.