There's nothing simpler or more habitual than turning on a tap to get some water. Yet we don't always realize that behind this commonplace gesture lies the implementation of complex means and technologies.  In fact, water extracted from nature often lacks the physical, chemical and biological qualities desirable for consumption. Surface water, which is harnessed by means of dams, reservoirs and river intakes, accounts for the bulk of available water resources. As a result, they are practically the main source of raw water for drinking water plants.