Athi water rolls out KSh76.3bn projects to expand Nairobi water supply

Athi Water Works Development Agency (AWWDA) is implementing a KSh76.3 billion portfolio of water and sanitation projects targeting Nairobi, Kiambu and Murang’a counties as demand for essential services continues to grow across the metropolitan region.

The investments cover bulk water supply, treatment facilities, transmission and distribution networks, storage reservoirs, sewerage systems and wastewater treatment infrastructure. The programme targets a region with a population of more than nine million people, with interventions intended to improve water reliability, expand household connections and strengthen sanitation services.

One of the major developments is the operational Northern Collector bulk water supply system, which is supplying 140 million litres of treated water daily to Nairobi. The system forms part of efforts to increase bulk water availability in the capital, while additional infrastructure is being developed to extend supplies to more neighbourhoods.

AWWDA has also completed offtake infrastructure at Runda, Karuri, Two Rivers, Thindigua and Kiambu to support further distribution investments.

In western Nairobi, ongoing infrastructure works include 24 kilometres of transmission pipelines, 54 kilometres of distribution networks and a reservoir in Karen. Meanwhile, the strategic transmission link along the Gigiri-Karura-Outer Ring corridor has reached 72.3 per cent physical progress, with more than six kilometres of pipeline already laid.

The agency is also pursuing last-mile connectivity through proposed distribution works linked to the Northern Collector Tunnel. The planned network covers approximately 400 kilometres of pipelines and targets more than 300,000 people in areas including Syokimau, Gatani, Mihang’o, Utawala, Ruai, Kamulu and Thindigua.

In Kiambu County, the Gatundu Water Supply and Sewerage Project is nearing completion. The project includes a treatment plant with a production capacity of 18,000 cubic metres daily, water pipelines and 2,000 household connections. Other interventions include the operational Ruiru-Juja/Greater Githurai project and the completed Mwihoko last-mile project, which has been handed over.

Beyond water supply, the agency is expanding sewerage infrastructure through the Nairobi Rivers Basin Rehabilitation and Restoration Programme under the Nairobi River Sewerage Improvement Project Phase II (NaRSIP II).

The programme targets an increase in Nairobi’s sewerage coverage from 48 per cent to 55 per cent, with more than 400,000 residents expected to benefit by the end of 2026. Work already completed includes approximately 65,000 household connections, more than 480 kilometres of sewer lines and the construction or rehabilitation of 50 ablution blocks in informal settlements.

At the Dandora wastewater treatment facility, additional investment is expected to increase treatment capacity by 20,000 cubic metres daily. The expansion is intended to improve wastewater management and reduce pollution entering Nairobi’s rivers.

The agency is also adopting alternative technologies to improve infrastructure maintenance. In Nairobi’s Central Business District, trenchless methods, including pipe-bursting and pipe-cracking, are being used to rehabilitate ageing underground pipelines while reducing excavation and disruption to roads and businesses.

Renewable energy is another component of the programme. Under the Athi Cluster Solarisation Project, solar power is being integrated into water and wastewater facilities in Limuru, Kikuyu and Machakos to reduce dependence on conventional electricity and improve operational resilience.

Alongside projects under implementation, AWWDA is preparing additional investments, including Thiririka Dam, Maragua IV Dam, Kiambaa-Ruiru II Dam, the Nairobi Metropolitan Bulk Water Supply Project, the Nairobi Satellite Towns Water and Sanitation Improvement Programme and NaRSIP Phase III.

The proposed Maragua IV Dam is estimated to require approximately KSh60 billion, while Thiririka Dam is valued at KSh18 billion and is expected to include a dam, treatment plant, pipelines and storage reservoir.

The proposed developments are intended to increase water storage and supply capacity as population growth and urban expansion continue to put pressure on existing infrastructure.

The scale of the investment highlights the growing need for integrated planning across water production, transmission, household distribution and wastewater management. For Nairobi and neighbouring counties, the long-term impact will depend on completing ongoing works and ensuring that additional bulk water supplies are connected to distribution systems capable of reaching households and businesses.