Blanket testing was carried out in 179 villages in Upper Indus Basin of Punjab, Pakistan. Out of total 19551 wells tested, 79% were found to have arsenic levels within WHO prescribed limit of 10μg L−1 while 11% had arsenic levels within National limit of 50 μg L−1. Ravi flood plain was found to be comparatively more contaminated than the rest of the study area. The prevailing redox conditions for arsenic release in Punjab is found to be mixed in nature, with conditions reducing enough for Fe oxide reduction but typically not enough for complete reduction of SO4.