the latest groundwater report of Karnataka, brought out by the Department of Mines and Geology (dmg) , shows that entire Bangalore is an overexploited zone. The 2004 study puts 55 taluka s in the overexploited category. The situation is worst in Kolar and Tumkur, apart from Bangalore's rural and urban areas. Besides the quantum of the resource, the quality of groundwater in Bangalore city is also alarming due to contamination with sewage and industrial effluents. Groundwater meets 40 per cent of the city's domestic potable water needs.

An analysis of 918 water samples collected from 735 locations shows that at 370 locations, the groundwater is not suitable for domestic use as per the specifications of the groundwater quality report of Bangalore city, 2003. Iron content in the groundwater was over 1 milligramme per litre (mg/l) in many places; the permissible limit is 0.3 mg/l. Of the 918 samples, 116 had iron content over 1 mg/l; at a few locations, it was over 6 mg/l.