About 90 percent of the county’s water resources comprise of both surface and ground water resource potential. Domestic water supply has recorded a noticeable growth over the last 5 years; 35 percent of the population have access to potable water

After coming into Law of the Water Act 2002, Athi Water Services Board (AWSB), a parastatal in the Ministry of Water and Irrigation which licensed nine (9) Water Service Providers (WSPs) Companies namely: Limuru Water and Sewerage Company, Kikuyu Water and Sewerage Company, Kiambu Water and Sewerage Company, Karuri Water and Sewerage Company, Githunguri Water and Sewerage Company, Ruiru- Juja Water and Sewerage Company Limited, Gatundu South Water and Sanitation Company, Karimenu Water and Sanitation Company and Thika Water and Sewerage Company Limited.

The Water Companies mainly cover the areas which had Water Schemes operated by Government or Municipalities and they had mainly concentrated in extending and improving water and sanitation services in their areas of operation.