When people were able to reach the near-Earth space, it turned out that the Earth is very small. And the view from above shows how much has already managed to mess things up man. Particularly severe consequences of human activities have affected water. This led to the fact that drinking water must be pre-cleaned, and the multi-stage purification begins to grow exponentially. Typical solutions include a drum grid complex reagent agriculture, non-pressurized filter system with a sand filling, disinfection with chlorine or hypochlorite, and washing water purification system with a makeweight in the form of a method of dewatering. All this takes a monster vast territory as, in fact, the technological production, and in the sanitary protection zone. While still in Russia, the land price has not, but indirectly the cost of starting to get the owners. About the same situation exists in wastewater treatment, wastewater composition today is very different from what is thrown our ancestors, and treatment facilities remain at 30 years of xx century.
There are attempts to improve the technology, but the way this extensive and reduces mainly to attempts to modernize long-established system of sewage treatment plants. This is clearly seen when viewing the patents in the field of water purification and sanitation. ( Differs in that the nut has four sides instead of six ). Events of recent years have shown that earthlings are several technologies that allow for harnessing the creative approach to design radically alter the effectiveness, and most importantly the principle on which to base water purification.