In most developed nations water is piped to homes, and is available on tap. The provision of tap water requires a massive infrastructure of piping, pumps, and water purification works. The cost of tap water is a small fraction of bottled water.

The same water supply that is used for drinking is also used for washing, flushing water closets, washing machines and dishwashers. Experimental attempts have been made to introduce non-potable greywater or rain water for these secondary uses.

Public health authorities in many areas have used the public water supply as a means of mass medication through the introduction of fluoridation. This remains a controversial issue in terms of the health, freedoms and rights of the individual.

The availability of clean tap water brings major public health benefits. Usually, the same administration that provides tap water is also responsible for the removal of waste water.

See also: Water resources, electrokinetics