Thanks to Treehugger I learned that
The "Life Saver" water bottle can purify 4,000 - 6,000 liters with one filter...
Four hours after Mr Pritchard launched his new "Life Saver" bottle at the DESI defence show in London yesterday [9/12/07], he sold out his entire 1,000 stock. "I am bowled over," he said.
Most filters eliminate bacteria but not viruses (25 nanometers in length), Pritchard's filter works to 15 nanometers. The "Life Saver" was awarded the "Best Technological Development" at the recent Soldier Technology conference.
The "Life Saver" costs £190 a pop.
The Lifestraw filters particles from 125 micron down to 15 micron for at least 700 liters.
About a year's supply of water costs $3 a pop.
Filtering bacteria and viruses is one thing, reducing heavy metals is another. Fortunately, there are simple ceramic heavy metal filtration systems available.
The fact that ceramic filters can be manufactured and produced by local ceramists with local materials makes them particularly attractive as a household water treatment technology that is affordable, appropriate, and sustainable. Some examples include the Potters for Peace Filtron (Nicaragua), the TERAFIL terracotta filter (India), and the candle filter (India, Nepal, Bangladesh, Brazil, etc).
Susan Murcott of MIT has a couple of decades worth of experience in the field, provides information on pilot projects in Nepal, Kenya, Haiti Nicaragua, Peru, Dominican Republic, and Ghana, and is part of the WHO household water initiative.
There's also solar water desalination
Over 1 billion people are without access to safe drinking water, every day over 5000 individuals die by drinking unsafe water through dysentary, cholera, and other waterborn diseases.