Humans are part of the natural water cycle.
All life depends on the health of this cycle but excessive pollution and consumption can create problems - our water use may become unsustainable. There is plenty that people can do to maintain the quality of freshwater and sea water and to ensure that its supply can be continued, even in times of drought. A failure to manage any of these areas properly could result in deterioration of water that we need for our well being. That's about 250 litres per person per day. Supplying such a large quantity of freshwater to the population requires a complex system of pipes - reticulation.