Surface waters are most vulnerable and affected by pollution and sewage flows. More then 50% of total pollution found in water sources comes from the air. 120 million people in pan-European region do not have access to safe drinking water, and even more have no access to sanitation.(see here) At least half the population of the Russian Federation is estimated to be at risk from unclean water as a result of aging infrastructure and the high cost of disinfectants. At the same time about 60% of the European cities with more than 100 000 inhabitants (or a total of 140 million people) are supplied with water from overexploited groundwater resources.(see here). Only 2.5% of the world's water is not salty, and two-thirds of that is locked up in the icecaps and glaciers.(see here). It becoming obvious that present water sources cannot provide enough water for all domestic use. Use of bottled water brought another new troubles with pollution and increased carbon footprint. Supplying a high quality potable water for all domestic use becoming very questionable. (blog here or here).