@subzero, since the enactment of Water Act 2002, there is no City, Municipal, Town nor county Council that provide Water Supply and Wastewater (sewer) services.
On source of water, that is not important as long as the water is treated before supply. FYI, there are no water and sanitation companies around Nairobi metro that provide adequate water, so, use the little you get sparingly.
On sewerage, i was in the team that designed ruiru sewerage system, and Athi Water Services Board have put the project as a priority but will take some time since the design will need to be revised due to the unexpected settlement pattern ithat we had not foreseen. The construction of the bypass and superhighway have messed the sewer pipes design and treatment works design.
Receive with simplicity everything that happens to you.” ― Rashi