An exposé by NTV has traced how city vendors source their water cheaply from informal settlements and then charge exorbitantly prices for the precious commodity.
Nairobi residents have been contending with water rationing for years now after diminished supply from the city's main source, the Ndakaini Dam.
Governor Mike Sonko had in June toured the dam but said water rationing will continue indefinitely due to insufficient water levels.
Water vendors in Nairobi have taken advantage of the desperate shortage to mint money by overcharging their captive customers.
The investigation by NTV revealed how vendors mostly get the water from informal settlements where water supply in heavily subsidised by the county government.
"Tunaskia huko slums maji haiwezi potea juu naskia wanalipiwa na bank," said moses Wanyonyi during an interview with NTV.
The estates most suffering from water shortage include Lang'ata, Umoja, Jamhuri, Harambee, some parts of Buruburu and Komarock.
City residents have complained of staying for months without getting water forcing them to look for alternative means.
"I have not received consistent water supply from the county for the last four months. We have to buy water after every two weeks and that is costing me like in a month five thousand shillings," said Catherine Ouma, a resident in Lang'ata.
Earlier this year the Nairobi Water and Sewerage Company acting managing director Engineer Nahashon Muguna said Nairobi residents will continue grappling with water rationing until 2026 when more dams will be completed.
He explained that Ndakaini dam's storage has fallen by 49 per cent to 34 million cubic metres.