Water use

DEFINITION: Consumption of fresh water by residences, businesses, industries, governments, and agricultural interests in support of human populations

Human beings’ use of fresh water has numerous impacts on the environment, in part because available freshwater resources, like mineral resources, are unevenly distributed, necessitating the transport of water over long distances.

Although water is the most abundant liquid on the planet and can be found almost everywhere, 97 percent of it is too salty for human use. Of the remainder, about 68.7 percent is frozen in icecaps and glaciers. Raw freshwater can come from either surface or ground sources. Surface sources include river systems, lakes, and reservoirs. Groundwater sources vary from unconsolidated materials, such as the sandy deposits along the Atlantic and Gulf Coastal Plain and the stratified sands and gravels of glaciated areas, to consolidated rocks, such as sandstone and shale, where water is obtained from the fractures within the formations. Water-supply systems that rely on groundwater can vary in size from a few wells serving a small community to a network of many wells serving a larger area, such as the Suffolk County Water Authority in Long Island, New York.

Types of Water Uses

Water for public supply needs is defined as water that is delivered to multiple users for domestic, commercial, and industrial purposes, as well as for firefighting, street washing, and municipal parks. The purveyor may be either public, such as a city-run utility, or private (an example is American Water, an investor-owned company that serves communities in several states). In the United States, public systems that deliver potable water to a variety of users must comply with federal and state standards for safe drinking water. In public systems, the water’s source and quality are subject to routine tests to ensure regulatory compliance.

Domestic water use is defined as the use of water for normal household purposes, such as drinking, food preparation, bathing, washing dishes and clothes, toilet flushing, lawn and garden watering, and home car washing. Households that obtain their water from on-site wells are not part of the public potable water system infrastructure. The number of households in the United States that fall into this self-supplied category is substantial. The federal Environmental Protection Agency (EPA) reports that approximately 15 percent of the US population—more than 15.8 million housing units, according to census data—are served by their own private drinking-water supplies. Although these supplies are not regulated by the EPA, some state and local governments set standards for private wells. Self-supplied domestic water systems are rarely metered, and minimal data exist as to the amounts withdrawn.

Industrial water use includes the use of water necessary for processing, washing, diluting, cooling, and in factories that make a variety of products. Industries that use large amounts of water include the steel, chemical, paper, and petroleum-refining industries. Of the industrial uses of water, thermoelectric power constitutes a substantial water-use category in itself. It includes water used for electric power generation from fossil-fuel, nuclear, or renewable energy sources. Most of the water used by thermoelectric plants goes for condenser and reactor cooling. Only a small fraction of the water used in this category comes from public water systems. Another industry, mining, is also in a category by itself. Mining water use includes quarrying, crushing, washing, and other activities associated with extraction operations.

Irrigation water use includes water employed to sustain plant growth in agriculture and horticulture. It encompasses the use of water not only for watering plants but also for applying agricultural chemicals, controlling weeds, preparing fields, cooling crops, suppressing dust, protecting against frost, and harvesting. Larger-scale nonagricultural irrigation—of golf courses, parks, nurseries, cemeteries, and the like—are included in this category.

Livestock water use is that associated with the farming of dairy and beef cattle, sheep and lambs, goats, hogs and pigs, horses, and poultry. It includes water devoted to livestock watering, feedlots, dairy operations, cooling of animal facilities, facility sanitation and washdown, and animal disposal systems. Similarly, aquaculture water use is that associated with sustaining organisms that live in water, notably finfish and shellfish. Aquaculture, which involves controlled feeding, sanitation, and harvesting of aquatic organisms, may be conducted for food, restoration, conservation, or sport purposes.

In 2015, total US water use was about 322 billion gallons per day. In 2010, thermoelectric power plants used 45 percent of the nation's water; irrigation used 32 percent; public supply accounted for 12 percent; self-supplied industry used 5 percent; aquaculture used 3; and mining accounted for 2 percent.

Water Consumption Trends and Conflicts

In 2015 in the United States, California and Texas were responsible for 16 percent of US water withdrawals. These two states along with Idaho, Florida, Arkansas, New York, Illinois, Colorado, North Carolina, Michigan, Montana, and Nebraska accounted for 50 percent of US water withdrawals. Florida, New York, and Maryland accounted for 50 percent of saline water withdrawal.

Water use in most countries is a function of served. Consequently, as the population increases, water consumption also increases, which means that water purveyors continually need to expand their water-supply sources. The need for additional supplies of water has resulted in innumerable sociopolitical disputes over the years. In arid areas such as the Middle East, water is crucial for general use and irrigation; thus the decision by Turkey in the late twentieth century to build large reservoirs in the headwaters of the Tigris and Euphrates rivers caused friction between that nation and the downstream states of Syria and Iraq, which objected to the prospect of being deprived of a portion of the flow on which they had historically depended. The allocation of the Jordan River among Israel, Jordan, Syria, and Lebanon in another politically sensitive arid area is intimately related to the possibility of sustained peace in the region. Egypt is dependent on the Nile River, which originates in Ethiopia and Lakes Albert and Victoria in East-Central Africa. Thus, when upstream African countries began negotiating a cooperative framework to revise water-sharing arrangements in 2010, concerns over the impact of major irrigation and hydropower projects upstream caused Egypt to oppose the agreement.

Balancing water use and the availability of water requires serious effort at local, state, national, and international levels. Even with prudent planning and cooperation among parties, drought, desertification, water pollution, and population expansion increase the likelihood that water-use conflicts will arise.

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