Nairobi's new sewer plan ends 'flying toilets' in Mukuru slums

An open sewer mixed with 'flying toilets' in Nairobi. [David Njaaga, Standard]

For Catherine Nduku, a mother of three in Nairobi’s Mukuru kwa Njenga informal settlement, the onset of evening used to bring a familiar dread. 

The family’s only toilet was a shared pit latrine across a dark, muddy path, a perilous journey she feared for her children.

“At night, I feared letting them go alone,” Nduku said. “We mostly used plastic bags as a substitute for toilets. I would then discreetly discard the bag as far as possible.”

These so-called “flying toilets” – plastic bags of human waste discarded into the environment – were a humiliating and hazardous fact of life for thousands in the sprawling informal settlement.

The air was thick with the stench from latrines, and flies were a constant nuisance. Today, that changed. A new simplified sewer system, a key part of the government’s plan to overhaul sanitation in Nairobi’s crowded informal settlements or slums, has brought a clean toilet to a unit just outside her door.

“The air is fresher, and my children can play without stepping into waste. I no longer panic when the rains start,” Nduku said. “The pipes keep everything flowing so there is no more sewage running past our homes.” The project, led by the Nairobi City Water and Sewerage Company (NCWSC), represents a strategic shift in how the government is tackling a sanitation crisis. 

With some official studies estimating that 60 per cent of Kenyans will never be connected to a conventional sewer, this decentralised model is seen as a sanitation revolution that can restore dignity for slum dwellers. 

The core of the plan is what Nairobi Water experts call “simplified sewer technology.”  Unlike conventional systems that require deep, wide trenches for large pipes, this approach uses smaller, flexible pipes laid at shallow depths along existing plot boundaries and footpaths.

This technical breakthrough is seen as critical in Mukuru’s dense, informal terrain, where narrow, unpaved corridors wind between homes.

“A conventional sewer would have meant deep trenches in the middle of already narrow roads and the risk of displacing families and businesses,” said NCWSC acting Managing Director Martin Nang’ole. The State agency is the architect of the new programme. 

“Our simplified approach gave us the flexibility to work with the people of Mukuru, not against them.”

Capital cost

Nang’ole, who has called the project a “practical innovation for public good,” stated that the capital cost was roughly Sh20,000 per household, a fraction of the approximately Sh195,000 per household for a conventional system in a similar area. 

He sees this cost-effectiveness as central to the government’s plan to scale the project and tackle a sanitation crisis. “The Mukuru simplified sewer system works out to roughly Sh4,000 per person... A conventional sewer in a constrained informal settlement is typically eight to 10 times more expensive,” Nang’ole said, underlining the financial viability he believes makes it a template for informal settlements in the country.

Beyond the obvious health and dignity benefits, the project has delivered tangible economic relief, officials and residents say. Residents like Isaac Otieno, a community trainee, previously had to budget for pay-per-use latrines. “Every morning before I left for work, I had to leave money for water and use of the latrine. It was very expensive,” Otieno said.  He estimates his family was spending Sh1,200 a month. “Now I save money that we were using to use the toilet. I can buy food and pay school fees.”

The project’s sustainability is designed around a modest monthly fee of Sh20 per household. Nang’ole said the price was set to keep sanitation affordable while supporting basic maintenance. The utility is also training local community-based organisations to help manage and maintain the system, fostering a sense of ownership. “Also, being trained to maintain the system gives us a sense of responsibility. If something happens, we are the first to respond. We feel trusted,” Otieno said.

This local involvement helps overcome what Nang’ole identified as the single biggest hurdle: building trust.

“When you enter a dense informal community and start digging near homes and businesses, people want assurance that you are adding value, not creating problems,” he said. 

“Once residents saw that we respected their space and were serious about improving living conditions, the project gathered momentum.” For landlords like Brian Wasike, the project has also been a financial boon.