Water conservation is a practice in which people, companies, and governments attempt to reduce their water usage. The goal of water conservation may be to address an ongoing water shortage, or to make lifestyle modifications to be more environmentally friendly. In the late 20th century, water emerged as a major issue, especially in the developing world, where many people lack access to safe drinking water, and the issue of water conservation began to attract a great deal of attention.

One of the most obvious reasons to practice water conservation is in a situation where water supplies are limited. An ongoing drought can restrict supply, as can a change in water policy, especially in an area where people are dependent on water from other places. Desert regions, for example, rely on water which is shipped, trucked, or moved through aqueducts, so distant policy decisions can directly impact the amount of water which can be accessed in these areas.

Water conservation may also be practiced in response to rising water prices. The cost of water is usually contingent on how easy it is to access, how far it must be transported to reach the end consumer, and how much it needs to be processed in order to be rendered safe. Water treatment can get extremely expensive, causing water prices to rise, and water prices also grow when water supplies are tight. From an economic standpoint, water conservation keeps water bills down to a manageable level, and it frees up water for other uses.

Some people encourage the practice of water conservation because they would like to promote the sustainable use of water. While water is a renewable resource in a sense, every time fresh potable water is used, it takes a long time for that water to re-enter the water supply, as it may become contaminated by chemicals, biohazardous materials, and so forth, requiring extensive cleanup before it can be re-used. Using water for things like gardens, car washing, and industrial production may be frowned upon in some communities where people would prefer to reduce the overall amount of water they use so that clean water will be available to future generations and other regions of the world.

A water conservation order may be issued to oblige citizens to conserve water in some communities. Conservation orders are often issued when water supplies are low, and officials are worried about running out. They may also be used to mandate water conservation for environmental reasons. Typically, water conservation orders restrict water use by setting rules about how and when water can be used.