The Thika River flows through Kiambu County in central Kenya and is a tributary of the Tana River. The river forms a psychological boundary between the counties of Murang'a and Kiambu. The Thika River is a significant source of hydroelectric power in Kenya and provides most of the water supply for Nairobi, Kenya's capital and largest city.
The name Thika originates either from the Kikuyu language or from the Maasai language.[1] It may relate to the Kikuyu word guthika, which means to bury.[1] It also resembles the Maasai word sika, which means to rub something away from an edge.[1]