WATER SUPPLY FROM THE DAMS AND SPRINGS The bulk of water supply for Nairobi comes from Thika, Sasumua and Ruiru Dams, as well as the Kikuyu Springs. Over time water supply for the city has failed to meet demand. The current estimated water demand for Nairobi is 650 000 m3 day compared to the production of 482 940 m3

/ /day (WRMA

2010). The difference between production and demand has been widening over time due to population growth, inadequacy of the carrying capacity of the distribution network and climate shocks.

GROUNDWATER SUPPLY Nairobi also depends on groundwater drawn from the Nairobi Aquifer Suite, which covers an area of approximately 3 000 km2

.

The most important natural recharge area for the acquifer is the southern Aberdare and eastern Rift escarpment, including the Ngong Forest. Of the total recharge area of 986.27 km2

, 450 km2

is either under forest cover or swamp, while the rest is under intensive cultivation. Further loss of the forest will have direct impact on deep aquifer recharge. In addition, increased use of pesticides in the agro-zone of the recharge area will increase the levels of contaminants in the recharge water (WRMA 2010).

Groundwater abstractions in the Greater Nairobi Area started in the early 1950s. In 2002 the city had 1 350 boreholes withdrawing about 70 000 m3

/day (Mogaka and others 2006),

and representing 21 per cent of the water supply to the Nairobi area (Mogaka and others 2006). A recent study (WRMA 2010) established that there are about 4 800 boreholes in Nairobi with a total annual abstraction of 58 million m3 groundwater accounts for 65 000 m3 needs, 60 000 m3

for livestock uses and 28 000 m3 of the Nairobi Aquifer Suite catchment area (WRMA 2010).

There is evidence that the rate of groundwater abstraction is imbalanced, with over-abstraction in some areas while extraction in other areas is within “sustainable limits” (Mogaka and others 2006, WRMA 2010). The Water Resources Management Authority has identified several groundwater hotspots6

in the

Nairobi environs, the most notable being (WRMA 2010): • Westlands, with 118 boreholes and a concentration of 20 boreholes per sq km;

6. The term hotspot is used to refer to areas where there is an existing or emerging high demand for groundwater.

26 300 500

/day for industrial purposes, 3 000 m3 /day for irrigation in the whole

. Estimates show that /day of domestic water /day

• Kikuyu, with 90 boreholes and a concentration of 16 boreholes per sq km;

• Karen, with 61 boreholes and a concentration of 9 boreholes per sq km;

• Ongata-Rongat, with 45 boreholes and a concentration of 8 boreholes per sq km; and

• Thika, with 33 boreholes and a concentration of 6 boreholes per sq km.

PRO-POOR WATER SUPPLY MEASURES The 200 slum settlements in Nairobi have inadequate safe drinking water and sanitation facilities. Kibera settlement, for example, receives about 20 000 m3

of water per day, 40 per

Water supply and demand in Nairobi Cubic metres per day

700 Daily demand 600 WATER DEFICIT

400 Daily supply

200 April 2008 Source: NCWSC, 2010.

Figure 6: As the population of Nairobi expands, the pressure on water supply increases and the gap between supply and demand grows.

January 2009 January 2010