Where does Kenya’s wastewater go as sewerage coverage remains low?

Kenya’s growing urban population is putting increasing pressure on sanitation infrastructure, raising concerns about how wastewater from millions of households is collected, treated and disposed of.

With sewerage connections remaining limited across the country, many households continue to depend on septic tanks, pit latrines and other onsite sanitation facilities, highlighting the challenges facing the country’s wastewater management system.

The situation presents a growing environmental and public health concern, particularly in rapidly expanding towns where housing developments are increasing faster than sewerage infrastructure.

Sewerage coverage is estimated at just 16 per cent nationally, meaning that most households are not connected to public sewer networks. This places additional responsibility on onsite sanitation systems, which require proper construction, regular emptying and safe disposal of collected waste.

Where these systems are poorly maintained or lack access to regulated emptying services, wastewater can find its way into drainage channels, rivers and surrounding environments.

The scale of the challenge is reflected in the 2024/2025 water sector performance report published by the Water Services Regulatory Board (WASREB). The report shows that the population served by sewerage systems in regulated water utility areas increased from approximately 4.76 million to 5 million, representing only 16 per cent of the population within those service areas. 18 Report.indd

Data from the United Nations Sustainable Development Goal 6 monitoring platform further illustrates the extent of the problem. In 2024, sewer networks accounted for only 12 per cent of domestic wastewater generated in Kenya, while septic tanks contributed 14 per cent and other sanitation facilities accounted for 74 per cent. SDG 6 Data

The figures raise questions about the capacity of existing sanitation systems to safely handle waste generated by households, businesses and institutions.

One of the major concerns is the disposal of faecal sludge collected from septic tanks and pit latrines. Without adequate treatment facilities and regulated transportation, collected waste can end up in inappropriate disposal sites, exposing communities and water resources to pollution.

The problem also extends to rivers and groundwater sources, which are important for domestic consumption, agriculture and industrial activities. Wastewater entering these systems can introduce harmful pollutants, creating additional treatment costs and environmental risks.

Speaking during the second Water, Sanitation and Irrigation Conference in Nairobi on October 23, 2026, Alex Manyasi, Policy Engagement Manager at the African Population and Health Research Centre, called for a review of the Water Act to address gaps relating to onsite sanitation.

Manyasi argued that the existing legal framework places considerable emphasis on conventional sewerage systems despite the large proportion of Kenyans relying on alternative sanitation facilities.

He warned that poorly managed waste could seep into rivers and underground water sources, with consequences extending to food safety where contaminated water is used for irrigation.

Addressing the challenge will require more than expanding conventional sewer networks. Investments in wastewater treatment plants, faecal sludge management, regulated waste transportation and improved onsite sanitation systems will also be necessary.

County governments and water utilities will need to strengthen coordination to ensure that waste collected outside sewer networks receives proper treatment and disposal.

For Kenya, improving wastewater management is increasingly becoming a water security priority. Protecting rivers and groundwater will depend not only on expanding clean water supply but also on ensuring that wastewater generated by growing communities is safely managed.