Water supply facts for kids
Water supply is the provision of water by public utilities commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Irrigation is covered separately.
Global access to clean water
In 2010, about 87% of the global population (5.9 billion people) had access to piped water supply through house connections or to an improved water source through other means than house, including standpipes, water kiosks, spring supplies and protected wells. However, about 13% (about 900 million people) did not have access to an improved water source and had to use unprotected wells or springs, canals, lakes or rivers for their water needs.
A clean water supply - in particular water that is not polluted with fecal matter from lack of sanitation - is the single most important determinant of public health. Destruction of water supply and/or sanitation infrastructure after major catastrophes (earthquakes, floods, war, etc.) poses the immediate threat of severe epidemics of waterborne diseases, several of which can be life-threatening.
Water supply systems get water from a variety of locations after appropriate treatment, including groundwater (aquifers), surface water (lakes and rivers), and the sea through desalination. The water treatment steps include, in most cases, purification, disinfection through chlorination and sometimes fluoridation. Treated water then either flows by gravity or is pumped to reservoirs, which can be elevated such as water towers or on the ground (for indicators related to the efficiency of drinking water distribution see non-revenue water). Once water is used, wastewater is typically discharged in a sewer system and treated in a sewage treatment plant before being discharged into a river, lake or the sea or reused for landscaping, irrigation or industrial use (see also sanitation).
In the United States, the typical single family home uses about 138 US gallons (520 l; 115 imp gal) of water per day (2016 estimate) or 58.6 US gallons (222 l; 48.8 imp gal) per capita per day. This includes several common residential end use purposes (in decreasing order) like toilet use, showers, tap (faucet) use, washing machine use, leaks, other (unidentified), baths, and dishwasher use.
Many of the 3.5 billion people having access to piped water receive a poor or very poor quality of service, especially in developing countries where about 80% of the world population lives. Water supply service quality has many dimensions: continuity; water quality; pressure; and the degree of responsiveness of service providers to customer complaints.
Continuity of supply
Continuity of water supply is taken for granted in most developed countries, but is a severe problem in many developing countries, where sometimes water is only provided for a few hours every day or a few days a week. It is estimated that about half of the population of developing countries receives water on an intermittent basis.
Water pressures vary in different locations of a distribution system. Water mains below the street may operate at higher pressures, with a pressure reducer located at each point where the water enters a building or a house.
In poorly managed systems, water pressure can be so low as to result only in a trickle of water or so high that it leads to damage to plumbing fixtures and waste of water.
Pressure in an urban water system is typically maintained either by a pressurised water tank serving an urban area, by pumping the water up into a water tower and relying on gravity to maintain a constant pressure in the system or solely by pumps at the water treatment plant and repeater pumping stations.