The middle and upper Ganga plains covering the upstream part from Rajmahal Hills, were earlier considered to be free from arsenic groundwater contamination. Initially, the contamination (>0.05 mg/l) was reported in 2002 from two villages, Bariswan and Simaria Ojhapatti of Bhojpur district of Bihar. Studies by the Central Ground Water Board and the Public Health Engineering Department, Government of Bihar have indicated the contamination as high as 0.178 mg/l in the surrounding villages, affecting the hand pumps which are generally of 20