While I recognize that your ...

While I recognize that your question is motivated by the acute need to respond quickly to the Earthquake emergency, both you and your readers need to recognize that most Nepali villages as well as Katmandu itself had a chronic problem of water contamination long before the recent earthquake. This problem was caused in large part because of the system of intermittent supply that prevails throughout most of Nepal. For example, the typical home or standpipe receives water for only a few hours per day and the rest of the time the pipes are largely empty and/or subject to negative (suction) pressure. Consequently, even if the water is treated at some central distribution point, by the time it actually reaches the consumer it is highly likely to have been recontaminated through contact with polluted surface drainage or even raw sewage. Fortunately, Nepal previously had an outstanding example of a cost-effective 24/7 water supply system in the village of Dhulikhel, Nepal in the Katmandu Valley. This system not only assured an adequate, affordable and sustainable water supply for the community but it was able to protect that water from contamination. Unfortunately, many of the people in the surrounding area did not fully recognize the value of this system and after successfully operating for over a dozen years it was allowed to revert to an intermittent system (3 or 4 hours per day) and consequently was no longer capable of protecting the water during delivery.