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Pilot demonstrates effectiveness of simplified sewers in Kenya

Themes: Customer experience Health impact Innovation Research Sanitation Sewerage Utilities WASH
Countries: Kenya

A pilot project in the informal settlement of Mukuru has demonstrated a cost-effective way to bring decent sanitation to some communities in Kenya: simplified sewers.

Most residents in Kenya’s densely packed informal communities lack access to decent sanitation, and the practical and financial challenges of addressing this crisis are well documented. However, new evidence shows that simplified sewer networks, which are much shallower and more flexible than traditional sewer systems, can form part of the solution. This opens up new possibilities for better sanitation which could benefit millions of Kenyans.

What is a simplified sewer?

Simplified sewers are widely used in South America. They use smaller and more flexible pipes, laid at a shallower depth, making them quicker, easier, and cheaper to lay. They work best in cities which have an existing sewer network of trunk sewers, as is the case in Kenya’s capital, Nairobi, allowing for the waste from the new network to travel into the main sewer system – and from there to treatment facilities.

In addition to trunk sewers, there are some other conditions required for simplified sewers to work, such as adequate water supply to support pour-flush toilets and strong community engagement to support operations and maintenance, including solid waste management and disposal.

Download the simplified sewers report

Connected to the main line, the simplified sewers network reaches homes within the Mukuru community

How it works: the simplified sewers network

These conditions were in place during the pilot project, which was a partnership between Water & Sanitation for the Urban Poor (WSUP), Nairobi City Water & Sewerage Company (NCWSC), Nairobi Metropolitan Services (NMS), Akiba Mashinani Trust (AMT), and the community in Mukuru.  With the financial support of The One Foundation, WSUP laid over 1000m of pipes, constructed 72 inspection chambers and connected 94 households to the sewer system, benefitting over 4,000 individual residents who now have pour-flush toilets. Prior to the intervention, most Mukuru residents relied either on shared pit latrines or pour-flush toilets which channelled waste through open drains to the nearby river.

Read the summary: the Nairobi simplified sewers pilot

Positive response from customers

Customer satisfaction with the improved facilities was found to be high, and many also benefit from reduced prices: residents of Mukuru pay between KES 5-10 for a single use of public latrines (amounting to KES 900 a month for a family of three), compared to KES 20 per month for simplified sewer services, assuming a plot of ten households.

“There is no ‘one size fits all’ solution to the sanitation challenge in urban slums”, explains WSUP’s Country Manager in Kenya, Eng. Eden Mati. “However, we now have strong evidence that simplified sewers are one of the answers. The prevalence of trunk sewer networks around many of our informal settlements in Kenya provides abundant untapped potential for scale-up of this solution. Further challenges lie ahead, not least in securing the finance for extending the connections and developing appropriate infrastructure for sewage treatment, but I am hopeful these can be overcome.”

Top image: the informal settlement of Mukuru, in Nairobi, Kenya

Learn more about WSUP's work in Kenya