In a village called Aam-bagan in Nagaon district of Assam Sumitra Biswas summoned her grandson to help her pour water into the filter kept in the courtyard of their house. The filter -- three buckets fitted with taps at three different levels -- was set up by the family itself through a simple DIY (do-it-yourself) method. Over the next one hour when the water was allowed to stand before being collected for safe consumption this seemingly simple filter removed arsenic (and also iron) -- a grave problem in Assam because of its devastating effects including causing cancer. Arsenic contamination of