Evidence... how about this: http://xkcd.com/903/ http://xkcd.com/903/ ? "Water purification" was this first thing that popped into my head based on your "basic

Evidence... how about this: http://xkcd.com/903/ http://xkcd.com/903/ ? "Water purification" was this first thing that popped into my head based on your "basic necessities" comment earlier. The article is in fact an extremely good starting point for a competent engineer with no special knowledge of the matter. It describes the issue and outlines solutions, with linked references to further research if needed. And yes, it is detailed enough to help very significantly. I tell you this as a practising engineer with little knowledge of water purification myself. I am surprised you think otherwise.