Water Use Concepts and Terms
Adapted from the National Handbook of Recommended Methods for Water Data Acquisition and Estimated Use of Water in the United States in 2000
- Water Use
- In the broadest sense, water use pertains to the interaction of human activity with and its influence on the hydrologic cycle and includes elements such as self-supplied withdrawal, public-supply delivery, consumptive use, wastewater release, reclaimed wastewater, return flow, and instream use. In a restrictive sense, water use refers to water that is actually used for a specific purpose, such as for domestic use, irrigation, or industrial processing. Water use is divided into two types, offstream and instream use.
- Aquaculture water use
- Includes farming of animals that live in water, such as fish and shellfish, within a confined space and under controlled feeding, sanitation, and harvesting procedures. Includes water used by fish farms and fish hatcheries.
- Domestic water use
- Includes water used for household purposes such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, car washing, and watering lawns and gardens. The largest components of domestic use can be inside household uses (bathing, flushing toilets, etc.) or outside household uses (lawn and garden watering, car washing, etc.) depending on the climate. The U.S. Department of Housing and Urban Development (1984) found that toilet flushing (39 percent) and bathing (30 percent) are the largest components of inside household use. Outside household uses range from near zero in humid areas to 60 percent of total domestic use in arid areas (U.S. Department of Housing and Urban Development, 1984). Domestic water may come from Public Water Supplies or be Self supplied as from a private well.
- How large is a million gallons per day?
- One million gallons would form a cube that is 51.1 feet on each side. A million gallons per day (Mgal/d) as a rate of flow of water is equal to 133,680.56 cubic feet per day, or 1.5472 cubic feet per second, or 3.0689 acre-feet per day. A flow of one million gallons per day for one year equals 1,120 acre-feet (365 million gallons).
- Industrial water use
- Includes withdrawals. Water used for industrial purposes may be incorporated into products or used for processing, washing, cooling, sanitation, or maintenance. The five major industrial groups defined by the Standard Industrial Classification (SIC) codes (U.S. Bureau of the Census, 1986) that use the most water per facility are:
- SIC 20 - Food and kindred products; the manufacture or processing of foods and beverages for human consumption, and related products such as ice, vegetable and animal fats and oils, and prepared feeds for animals and fowls.
- SIC 26 - Paper and allied products; the manufacture of pulps from wood and fibers; the manufacture of paper and paperboard
- SIC 28 - Chemicals and allied products; the production of chemicals and chemical products such as drugs, cosmetics, and soaps
- SIC 29 - Petroleum refining and related industries; petroleum refining and the manufacture of paving materials, roofing materials, lubricating oils and greases
- SIC 33 - Primary metals industries; smelting and refining ferrous and nonferrous metals from ore, pig, or scrap; alloying metals; manufacturing nails, spikes, and insulated wire and cable
- Instream water use
- Occurs when the water remains in the stream (surface water), lake or pond, or aquifer (ground water) during use. Instream uses include hydroelectric power generation, recreation, hydroelectric power generation, transportation, waste assimilation, aesthetics, cultural resource preservation fish and wildlife preservation, biodiversity, wetlands preservation, freshwater dilution of saline estuaries, and maintenance of the riparian zone.
- Instream conveyance
- Occurs when water flows or is pumped from one reservoir to another without being used. Water may flow through a chain of reservoirs, from a river to a chain of lakes, from a river to a canal or aqueduct, or even from surface water to ground water. Quantitative estimates for most instream uses are undetermined, but are important because such uses compete with offstream uses and affect the quality and quantity of water resources.
- Irrigation water use
- Water that is applied by an irrigation system, to sustain plant growth in all agricultural and horticultural vegetation. It also includes water that is applied for pre-irrigation, frost protection, chemical application, weed control, field preparation, crop cooling, harvesting, dust suppression, and for the leaching of salts from the root zone. Water used for non-crop activities such as irrigation of public and private golf courses, parks, nurseries, turf farms, cemeteries and other landscape-irrigation uses may also be included in this subcategory.
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- Livestock water use
- Includes water associated with the production of meat, milk, poultry, eggs, and wool. The kind of stock includes dairy cows and heifers, beef cattle and calves, sheep and lambs, goats, hogs and pigs, and poultry. Poultry includes chickens, turkeys, ducks, geese, pheasants, and pigeons. Other water uses include evaporation from stock ponds, dairy and poultry sanitation or wash down, waste-disposal systems to process animal products, cooling of animals and products, and incidental water losses. Horses and other equines (SIC 0272), fur-bearing animals (SIC 0271) and Animal Specialties (SIC 0279) are part of the Livestock category. The Livestock category does not include on-farm domestic use, lawn and garden watering, or irrigation water use.
- Mining water use
- Includes water that is used for the extraction of minerals, ores and gases, which may be in the form of a solid, liquid or gas. Solid minerals include coal, ores, and sand and gravel operations. Liquids pertain to crude petroleum, and gases mostly pertain to natural gas.
- Offstream water use
- Occurs when water is withdrawn or diverted from a ground- or surface-water source for public-water supply, industry, irrigation, livestock, cooling for thermoelectric power generation, mining and domestic purposes. Sometimes it is called off-channel or withdrawal use.
- Withdrawal
- The quantity of water removed from a ground-water source to the point of use.
- Diversion
- The quantity of water removed from a surface-water source to the point of use.
- Delivery
- The quantity of water delivered at the point of use or treatment.
- Release
- The quantity of water released after use or treatment.
- Conveyance
- The systematic and intentional movement or transfer of water from one point to another, for example, from point of withdrawal to point of delivery; release from public water supplier to user; release from user to wastewater-treatment facility; after release to return flow. Withdrawals, deliveries, releases and return flows are the endpoints of conveyances.
- Conveyance loss
- Water that is lost in transit from a pipe, canal, conduit, or ditch by leakage or evaporation. Generally the water is not available for immediate reuse; however, leakage from an irrigation ditch, for example, may percolate to a ground-water source and be available for further use.
- Consumptive use
- That part of water withdrawn that evaporates, transpires, is incorporated into products or crops, is consumed by humans or livestock, or otherwise is removed from the immediate water environment.
- Return flow
- The quantity of water that is discharged after use or wastewater treatment to surface water or ground water so that it becomes available for reuse.
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- Public supply water use
- Includes water withdrawn from ground and surface sources by public and private water systems for use by cities, towns, rural water districts, mobile-home parks, Indian reservations, and military bases. Public-supply facilities include those providing water to at least 25 people, or a minimum of 15 connections. Water withdrawn by public suppliers may be delivered to users for domestic, commercial, industrial, and thermoelectric purposes. In addition, some public-supply water is used for water and wastewater treatment, public services such as pools, parks, and city buildings, or is lost through system leaks and maintenance. The Standard Industrial Classification code for the Public Supply category is 4941.
- Public-supply deliveries
- The amount of water delivered from a public supplier to users for domestic, commercial, industrial, thermoelectric-power, or public-use purposes.
- Self-supplied water
- Water withdrawn from a surface-water or a ground-water source by a user and not obtained from public supply.
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- Thermoelectric power generation water use
- This water use is defined as the amount of water used in the process of the generation of thermoelectric power. The source of the power may be from fossil fuels, nuclear-fission, or geothermal. Water is mostly used to cool the steam water. Two general types of cooling are once-through cooling and closed-loop cooling. Water withdrawal estimates are compiled for each type of cooling system.
- Once-through cooling
- Water that is withdrawn from a source, circulated through the heat exchangers, and then returned to a water body at a higher temperature.
- Close-looped cooling
- Water that is withdrawn from a source and then is recycled. This method uses cooling ponds and cooling towers to cool water before it is re-circulated through the cooling system.
- Units of measurement
- Water use is usually expressed as a rate, that is, a volume of water over a period of time. Common rates for water use are thousand gallons or 100 cubic feet, ccf, (as in a meter reading), gallons per minute, gpm, (as in pumpage), gallons per day, gpd, (as in per person or per household); million gallons per day, Mgal/d, (as in per facility or per geographically or politically bounded area); billion gallons per day, bgd, (as in a national total); or acre-foot, acre-ft, (more commonly used for irrigation water use and in the western United States).
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- Water withdrawal
- Water that is removed from a ground-water source or is diverted from a surface-water source for use.
References:
Hutson, S.S., Barber, N.L., Kenny, J.F., Linsey, K.S., Lumia, D.S., and Maupin, M.A., 2004, Estimated use of water in the United States in 2000: U.S. Geological Survey Circular 1268, 46 p.
U.S. Geological Survey, 1997, National handbook of recommended methods for water data acquisition -- Chapter 11 - Water Use: USGS, Reston, VA, available at http://pubs.usgs.gov/chapter11/ [computer file].
U.S. Bureau of the Census, 1986, Water use in manufacturing, census of manufacturers, 1982: Special Report Series MC 82-S-6.
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