• Nairobi will get an additional 140 million litres a day.
• The tunnel will collect 40 per cent of the floodwaters that flow into Maragua, Gikigie and Irati rivers.
Water shortage in Nairobi estates and parts of the Central region is about to end as the Northern Collector Water Tunnel nears completion.
The Sh20 billion World Bank-funded project was launched on September 18, 2012 and it is expected to be completed by June.
It is located in Murang'a county and entails the construction of a fully lined 11.8km tunnel with a diameter of 3.2m. The cost includes Sh6.8 billion spent on the tunnel, Sh6.5 billion on a treatment plant and Sh4.6 billion on a pipeline.
The tunnel starts at Ichichi in Kangema and runs through Kigumo before joining Gatanga at Ndakaini Dam, which is the main reservoir of water supplied to Nairobi and its environs.
Of the amount of water distributed within the city, Ndakaini contributes 80 per cent, Sasumua Dam 15 per cent, Ruiru Dam (three per cent) and Kikuyu Springs (two per cent).
Ndakaini produces 430 million litres of water a day, which is about 84 per cent of its supply to Nairobi and holds about 70 billion litres when full.
The tunnel will collect 40 per cent of the floodwaters that flow into Maragua, Gikigie and Irati rivers. Its water will be piped to the Gigiri reservoir before being distributed to Nairobi's Upper Hill, Eastlands, central business district, Westlands and Karen.
Under the plan, residents of Kiambu, Ruiru, Juja and parts of Thika will be allocated 50 million litres from the total water output.
Water Cabinet Secretary Sicily Kariuki said the project will also deliver upwards of 140 million litres of water per day to an additional 1.2 million residents.
“It is important to note that it is one of the single-most important projects in moving the Nairobi water coverage from the current 81 per cent to 86 per cent,” she said.
Many residents have experienced rationing since 2017, with some households going for days with dry taps, leaving them in the hands of exploitative vendors.
The city's current water demand is 790 million litres a day. It gets 526 million litres a day from Ndakaini Dam, leaving a shortage of 264 million litres daily.
The shortage is projected to worsen with the Nairobi Water Masterplan showing the city will require 1.2 billion litres of water daily by 2035.
Also being put in place is the Eastern Transmission Pipeline, which is 85 per cent done. The 24km project is scheduled to end at Embakasi, where a 14 million-litre reinforced concrete water storage tank has been erected.