Useful Terms & Concepts"the commons": any resource—like the oceans and the water we drink—that is shared by a group of people and should be preserved for future generations
conservation: the sustainable use of natural resources
desalination: removing salt, especially from seawater
ecosystem services: benefits obtained from intact ecosystems, such as water purification, waste breakdown, and oxygen production
grey water: wastewater from showers, sinks, and washing machines (not toilets)
groundwater: fresh water that is stored under Earth's surface in aquifers, layers of sand, gravel, or porous rock; groundwater supplies springs and wells
pesticides: any substance intended to kill unwanted organisms, especially insects. They can remain in the food web and water supply, with unintended consequences.
reclaimed water: sometimes called recycled water, this is former wastewater that has been treated and purified for reuse rather than discharged into a sewer or drain.
surface water: fresh water found on Earth's surface, such as rivers, lakes, and reservoirs
sustainable: meeting current needs without losing the ability to meet future needs
virtual water: the volume of water required to produce a commodity or service
wastewater: water, including sewage, that has been used in homes, industries, or businesses and cannot be reused unless it is treated
water cycle: the continuous movement of water between the atmosphere, the land, and the sea
water ethic: the concept that humans must protect the quality and availability of water for all the species that depend on it, now and in the future
water footprint: the total volume of fresh water used to produce the foods and services consumed by an individual or community
water stress: the combination of high human population and low water supply
waterborne disease: a disease caused by microorganisms (such as protozoa, viruses, bacteria, and intestinal parasites), and which is directly transmitted by drinking contaminated water
watershed: all the land drained by a single river system. Large watersheds like the Mississippi River basin contain thousands of smaller watersheds.
wetland: shallow, often intermittently wet habitat, such as a swamp or marsh. Wetlands help filter water, absorb the force of storms and tides, and provide habitat for countless species.