Tube well platform colour, as a proxy for identification of arsenic contaminated wells - case study from, alluvial aquifers of eastern India

Arsenic contamination in groundwater of Bengal basin was first reported in early 80s. Even after two decades of extensive research, our ability to pinpoint the arsenic-free sources, with precision, is limited. Proxies as indicator of arsenic concentration in groundwater are also lacking. It is imperative to formulate some cost-effective, user-friendly screening tool for the detection of arsenic safe wells. The present study utilises validation tests, colourimetry and statistics, to validate the platform colour hypothesis. Results show that red-stained platforms can identify arsenic-contaminated wells with 83% certainty; while black-stained platforms identify arsenic safe wells with 62% certainty, 78% sensitivity and 69% specificity. Black-coloured well platforms identify manganese-contaminated wells with 96% certainty; while red-stained well platforms mark manganese safe wells with 36% certainty and 93% specificity. The performances of such tests improve with increasing prevalence. A comprehensive colour chart thus prepared can be used as handy tool for identification of arsenic-contaminated wells.