The water shortage in Nairobi is acute and chronic. The prognosis is dire: It could get worse. Here is why: Inexorable demand owing to rapid urban growth; poor management of water demand; land use change and declining water supplies form source areas; climate variability and change; a dilapidated distribution infrastructure; and the stupefying ineptitude of the Nairobi Water and Sewerage Company.
In 2012 the Government of Kenya, the World Bank and the French Development Agency launched a master plan to develop additional supply capacity. This new plan includes the controversial construction of the Northern Collector Tunnel, which will transfer water from three rivers – the Maragua, Gikigie and Irati – to the Thika reservoir. This transfer is projected to increase Nairobi’s water supply to about 700,000 cubic metres.
As would be expected, the tunnel project has faced strong opposition from Murang'a residents and political leaders who expressed fears that the project might deplete underground water and cause earthquakes. However, Water Cabinet Secretary Eugene Wamalwa insists that the project will proceed and all issues associated with the impacts of the project have been addressed in accordance with stipulated procedures.
Inter-basin transfer through the Northern Collector Tunnel is a really bad idea ecologically, socially and economically. Ecologically, it is unsound because under current climate uncertainties such transfers are likely to severely deplete base water flows with the consequence of damaging riverine biodiversity, depleting downstream water supplies and diminishing groundwater recharge potential. In combination, these impacts will severely compromise socio-economic outcomes by undermining agricultural production potential for local farmers and constraining per capita access to freshwater supplies for local households.
Meeting water needs in the 21st century will require a paradigm shift. A starting point would be to make it mandatory for residential, commercial and industrial buildings to adopt measures of water use efficiency, water reuse and rainwater harvesting. It should be mandatory for households to install and use low-flush toilets to reduce water use per flush by 50 percent.
Wastewater or grey water from showers, baths, laundries and kitchens is relatively easy to reuse. With physical filtering and settling, grey water can be recovered for toilet flushing and gardening. And ecological engineering through constructed wetlands can be used for the treatment of wastewater and contaminated roof and urban storm runoff. Imagine how many new green jobs we could create!
Building the Northern Collector Tunnel is dumb economics and would touch off a social and ecological catastrophe.