Nairobi County has significantly increased its wastewater treatment capacity after expanding the Ruai Sewerage Treatment Plant from 160,000 cubic metres to 320,000 cubic metres per day, in a move aimed at improving sanitation services and supporting the city’s growing population.
The county government also announced plans to triple the capacity of the Kariobangi Sewer Treatment Plant from 30,000 cubic metres to 90,000 cubic metres per day while constructing a 54-kilometre trunk sewer network along the Nairobi River corridor.
The projects are expected to strengthen the city’s sewerage infrastructure, reduce pollution and improve wastewater management.
Ruai and Kariobangi upgrades to boost wastewater treatment
Nairobi Governor Johnson Sakaja said the expansion is necessary to meet the increasing demand for sanitation services as the city’s population continues to grow.
According to the governor, Nairobi hosts more than seven million people during the day and over five million residents at night, making it critical to expand sewer treatment infrastructure.
“This is important because we are in a growing city that now hosts more than seven million people during the day and over five million at night. It is paramount that we expand our treatment capacity, and that is exactly what we have achieved through the efforts of our teams in collaboration with the National Government,” Sakaja said.
County officials said the additional treatment capacity at Ruai, together with the planned Kariobangi upgrade, will ease pressure on the existing sewerage system and reduce the discharge of untreated wastewater into rivers.
New trunk sewer to help restore Nairobi River
The county is also implementing a 54-kilometre trunk sewer project in partnership with the national government to improve wastewater collection and disposal.
Sakaja said the new sewer line will replace illegal sewer connections that currently empty raw sewage into the Nairobi River and provide infrastructure capable of serving the capital for decades.
“The new trunk sewer line will serve Nairobi for the next 50 years. It will help clean the Nairobi River and permanently address illegal sewage discharges. Beyond environmental restoration, we are transforming the river corridor into an attractive public space with boulevards, walkways and cycling lanes, changing the story of a capital city that for decades has been defined by a polluted river running through it,” he said.
Project expected to improve sanitation and water reuse
County officials said the expanded Ruai treatment plant will also produce treated water that can be reused for agricultural purposes downstream.
Meanwhile, the planned expansion of the Kariobangi Sewer Treatment Plant is expected to enhance wastewater treatment services in northern parts of Nairobi while supporting future urban growth.
The sewer infrastructure projects form part of broader efforts by the county government to modernise Nairobi’s ageing sanitation system, improve environmental conservation and address challenges brought about by rapid urbanisation.
