Uses of Water

Water is one of the most vital natural resources for all life on Earth. The availability and quality of water always have played an important part in determining not only where people can live, but also their quality of life. Even though there always has been plenty of fresh water on Earth, water has not always been available when and where it is needed, nor is it always of suitable quality for all uses. Water must be considered as a finite resource that has limits and boundaries to its availability and suitability for use.

Figure 1. Offstream uses (depicted on the left) are those in which water is removed from its source, either by pumping or diversion. Instream uses (depicted on the right) are those in which water remains in place, and typically refers to stream (rather than groundwater). Where water supply is limited, conflicts may result between and among the various uses.

The balance between supply and demand for water is a delicate one. The availability of usable water has and will continue to dictate where and to what extent development will occur. Water must be in sufficient supply for an area to develop, and an area cannot continue to develop if water demand far outstrips available supply. Further, a water supply will be called upon to meet an array of offstream uses (in which the water is withdrawn from the source) in addition to instream uses (in which the water remains in place). Figure 1 represents the demands on water as a tug-of-war among the various offstream and instream uses.

Traditionally, water management in the United States focused on expanding or manipulating the country's supplies of fresh water to meet the needs of users. A number of large dams were built during the early twentieth century to increase the supply of fresh water for any given time and place. This era of building large dams has passed. In the twenty-first century, the finite water supply and established infrastructure require that demand be managed more effectively within the available sustainable supply. Water-use information can be used to evaluate the impacts of population growth and the effectiveness of alternative water management policies, regulations, and conservation activities.

The Water-Use Cycle

Water is constantly in motion by way of the hydrologic cycle. Water evaporates as vapor from oceans, lakes, and rivers; is transpired from plants; condenses in the air and falls as precipitation; and then moves over and through the ground into waterbodies, where the cycle begins again. ^*
The water-use cycle is composed of the water cycle with the added influence of human activity. Dams, reservoirs, canals, aqueducts , withdrawal pipes in rivers, and groundwater wells all reveal that humans have a major impact on the water cycle. In the water-use cycle, water moves from a source to a point of use, and then to a point of disposition. The sources of water are either surface water or groundwater. Water is withdrawn and moved from a source to a point of use, such as an industry, restaurant, home, or farm. After water is used, it must be disposed of (or sometimes, reused). Used water is either directly returned to the environment or passes through a treatment processing plant before being returned.

U.S. Water Withdrawals in 1995

The U.S. Geological Survey compiles nationwide water-use data every 5 years. The year 1995 is the last year for which full datasets are available.
As Figure 2 shows, the United States in 1995 used about 402,000 million gallons of water per day (MGD). Most of this water use was fresh water, about 341,000 MGD, or about 85 percent, while 60,800 MGD was saline water. The majority of fresh-water withdrawals, about 264,000 MGD, or about 77 percent, came from surface-water sources, while about 76,400 MGD came from groundwater. The source of saline water is surface water.
Even though discussions of water use typically focus on fresh-water use, saline water use also is important in the United States. Some categories of water use, such as thermoelectric, industrial, and mining, use saline water, mainly for cooling generators in thermoelectric power plants. Industries and mines use saline water to cool machinery and to wash and transport products, mainly for cooling of machinery.

Categories of Water use

The U.S. Geological Survey categorizes water use for analyzing current patterns and predicting future trends.
Commercial water use includes fresh water for motels, hotels, restaurants, office buildings, other commercial facilities, and civilian and military institutions. Domestic water use is probably the most important daily use of water for most people.
Domestic use includes water that is used in the home every day, including water for normal household purposes, such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens.
Industrial water use is a valuable resource to the nation's industries for such purposes as processing, cleaning, transportation, dilution, and cooling in manufacturing facilities. Major water-using industries include steel, chemical, paper, and petroleum refining. Industries often reuse the same water over and over for more than one purpose.
Irrigation water use is water artificially applied to farm, orchard, pasture, and horticultural crops, as well as water used to irrigate pastures, for frost and freeze protection, chemical application, crop cooling, harvesting, and for the leaching of salts from the crop root zone. Nonagricultural activities include self-supplied water to irrigate public and private golf courses, parks,

Figure 2. This illustration summarizes water withdrawals in the United States in 1995. The bar chart depicts fresh-water withdrawals (in billion gallons per day, or BGD). The table includes fresh-water and saline withdrawals (in million gallons per day, or MGD).

nurseries, turf farms, cemeteries, and other landscape irrigation uses. The importance of irrigation to the United States is illustrated by the large amount of fresh water that is used to cultivate crops, which are consumed domestically and throughout the world. In fact, irrigation is the largest category of water use in the United States, as it is worldwide.
Livestock water use includes water for stock animals, feed lots, dairies, fish farms, and other nonfarm needs. Water is needed for the production of red meat, poultry, eggs, milk, and wool, and for horses, rabbits, and pets. Livestock water use only includes fresh water.
Mining water use includes water for the extraction of naturally occurring minerals; solids, such as coal and ores; liquids, such as crude petroleum; and gases, such as natural gas. The category includes quarrying, milling (such as crushing, screening, washing, and flotation), and other operations as part of mining activity. A significant portion of the water used for mining, about 32 percent, is saline.
Public Supply water use refers to water withdrawn by public and private water suppliers, such as county and municipal water works, and delivered to users for domestic, commercial, and industrial purposes. In 1995, the majority of the nation's population, about 225 million, or 84 percent, used water delivered from public water suppliers. About 42 million people supplied their own water, with about 99 percent of that water being groundwater, usually from a local well.
Thermoelectric Power water use is the amount of water used in the production of electric power generated with heat. The source of the heat may be from fossil fuels, nuclear fission, or geothermal. Fossil fuel power plants typically reuse water. They generate electricity by turning a turbine using steam power. After the steam is used to turn the turbines, it is condensed back to water by cooling it. The condensed water is then routed back to the boiler, where the cycle begins again.

Trends from 1950 to 1995

After continual increases in the nation's total water withdrawals (fresh water and saline water) for the years reported from 1950 to 1980, withdrawals declined from 1980 to 1985 and remained fairly constant from 1985 to 1995. The 1995 estimate of total withdrawals (402,000 MGD) is about 2 percent less than the 1990 estimate and nearly 10 percent less than the peak year of 1980. Likewise, total fresh-water withdrawals for 1995 were about 8 percent less than in 1980.
The decline in withdrawals is especially significant in light of the fact that population posted an increase of 16 percent during the same period. Clearly as a nation, the United States is using its surface water and groundwater resources more efficiently. This decline signals that water use responds to economic and regulatory factors, and that the general public has an enhanced awareness of water resources and conservation issues.

Trends by Category

The public supply, domestic, and livestock categories are the only categories to show continual increases from 1950 to 1995, largely because of continual increases in population. The increase of 4 percent in public supply withdrawals from 1990 to 1995, compared to the population increase of 7 percent served by public supply, indicates that conservation programs have been effective in lowering public supply per capita use from about 184 gallons per day (GPD) in 1990 to 179 GPD in 1995.
More water continues to be withdrawn for thermoelectric power generation than for any other category. Withdrawals for thermoelectric power generation peaked in 1980 at 210,000 MGD and fluctuated around 190,000 MGD during 1985, 1990, and 1995.
Industrial withdrawals declined from 1980 to 1995 after remaining about the same for the years reported between 1965 and 1980. Lower industrial withdrawals are the result of new industries and technologies that require less water, improved plant efficiencies, increased water recycling; changes in laws and regulations to reduce the discharge of pollutants; and conservation measures.
Total irrigation withdrawals were about the same during the period from 1955 to 1960, then steadily increased from 1965 to 1980, and gradually decreased from 1980 to 1995. Irrigation application rates vary from year to year and depend on annual rainfall, surface water availability, energy costs, farm commodity prices, application technologies, and conservation practices. Declining application rates are the result of more efficient irrigation systems and techniques. Also, application rates in the more humid eastern United States, where irrigated acreage continues to increase, tend to be lower than in the arid western United States.

Figure 3. A chart of fresh-water withdrawals from 1950 to 1995 reveal trends in total water use and the relative withdrawals from groundwater and surface-water sources. (Values are in billion gallons per day, or BGD). The U.S. population also is depicted (in millions).

Factors Affecting Water-Use Trends

Figure 3 summarizes fresh-water withdrawals and population in the United States from 1950 to 1995. The general increase in water use from 1950 to 1980 and the decrease from 1980 to 1995 can be attributed, in part, to the following major factors:

• Most of the increases in water use from 1950 to 1980 were the result of expansion of irrigation systems and increases in energy development.
• The development of center-pivot irrigation systems and the availability of plentiful and inexpensive groundwater resources supported the expansion of irrigation systems.
• Higher energy prices in the 1970s, and large drawdown in groundwater levels in some areas increased the cost of irrigation water. In the 1980s, improved application techniques, increased competition for water, and a downturn in the farm economy reduced demands for irrigation water.
• The transition from water-supply management to water-demand management encouraged more efficient use of water.
• New technologies in the industrial sector that require less water, improved plant efficiencies, increased water recycling, higher energy prices, and changes in laws and regulations to reduce the discharge of pollutants resulted in decreased water use.
• The enhanced awareness by the general public of water resources and active conservation programs in many states have contributed to reduced water demands.

Future Water Use

Water-use trends established over the past half century provide some basis for estimating future water demands. It seems likely that water withdrawals for public supply and domestic uses will continue to increase as population increases. Higher water prices and active water conservation programs, however, may reduce the per capita use rates. With increased competition for water for instream uses, such as river-based recreation, aesthetic enjoyment, fish and wildlife habitat, and hydroelectric power, along with higher municipal uses, irrigators will have increasing difficulty competing economically for available water supplies.
In the United States, many existing sources of water are being stressed by withdrawals from aquifers and diversions from rivers and reservoirs to meet the needs of homes, cities, farms, and industries. Consideration must also be given to leaving water in the streams and rivers to meet environmental, fish and wildlife, and recreational needs.
As planners, managers, and elected officials wrestle with the varied water management problems facing the nation at the beginning of the twentyfirst century, they need consistent information on water supply and use by state, watershed, and water-use category. This will help the United States realize the maximum benefit from its water resources and will help strike that crucial balance between supply and demand.

How water is used

There are many, many ways that we use our water,

Seattle Locks Photo courtesy of US Army Corps of Engineers

and that is partly why it is so important that we conserve our water. Water is our most precious resource. Water is vital to life. Humans, plants, and animals are made up of mostly water. All living things would die if it weren't for water. We use water for drinking, washing, cleaning, cooking, and growing our food as well as many, many other things. The average American uses around 150-250 gallons of water daily. Even more water is used by industries to generate electricity, manufacture things, and transport people and goods.

Common household uses consume a lot of water. It may take between 30 and 40 gallons for one bath. The average toilet uses about 5 gallons of water per flush. It takes 20-40 gallons of water for one shower. Washing machines use an average of 25 gallons per load. The kitchen sink takes roughly 20 gallons per day for preparing food and washing dishes. The bathroom sink, used for washing hands, shaving and brushing teeth, requires about 15 gallons per day. These numbers are estimated for the average household in America.

Mowing Lawn Photo courtesy of FreeFoto.com

Much of our fresh water is also used outdoors for watering lawns, flower beds, and vegetable gardens, as well as washing cars and filling swimming pools. We must be careful not to pollute the water that we use outside. Many people use chemicals on their lawns and gardens and then water them with pure water. The water will wash the chemicals off of your plants and then run down a storm drain and go straight to the rivers and streams where fish make their homes. This kind of polluted water can kill fish and wildlife. We should always be mindful of whether or not we are polluting the water around us. We need to take care of our water, not abuse it.

Every town and city, whether small or big, uses water. Cities use water for fire fighting, street cleaning, and watering public areas such as parks, grass, trees, shrubs, and flowers. Water is also used to fill public drinking fountains, including those at schools and libraries. All of the different businesses in your community also use water. Think about all the water that is used by restaurants, hospitals, laundries, dry cleaners, golf courses, hotels, car washes, beauty shops, barber shops, gas stations, and health clubs as well as all of the other businesses in town. These all add up to quite a big demand on Washington's water supply. We need to try to think about how many people need to use water and conserve our water so that there is enough to go around.
The amount of water needed to run a farm is tremendous. When we think of water on a farm, we think of watering crops;

Beef and Dariy Photo courtesy of FreeFoto.com

but the amount of water needed on a dairy farm is a huge amount also. Chickens, pigs, sheep, and all the other animals in a farmyard need drinking water to stay alive. Food must be grown for them to eat, and water is also required in the cooling systems used to keep production meat fresh. Vegetable and grain crops also require water. Water is used in spreading fertilizers, herbicides, and pesticides, which produce a greater crop yield, but can also contaminate the water. Most of the water used on farms is used for irrigation. Studies show that by using drip irrigation, farmers can conserve up to 60% of the water that it would normally take to irrigate their crops using other systems of irrigation.

It takes about 26 gallons of water to produce one ear of corn while it takes about 2000-2500 gallons of water to produce one pound of beef. Around 120 gallons of water is required to produce one egg. About 300 gallons of water is needed to produce one loaf of bread, and it takes about 12,000 gallons of water to grow a bushel of wheat. Believe it or not, about 1,400 gallons of water are used during the final production of one fast-food meal including a burger, fries, and a soft drink.
Hydroelectric plants are the largest users of water.

Hydroelectric Dam Photo courtesy of ArtToday

Hydroelectric plants capture the kinetic energy of falling water to make electricity. They do this with a dam. The dam forces the water level to go up so that the water will have more power when falling. The force of the falling water pressing against the turbines' blades cause them to spin. The spinning turbines transmit the kinetic energy of the falling water to generators. The generators spin when the turbines spin generating electricity that will be transmitted on the power lines to homes and businesses.

Of all the electricity in the world, about 20% is generated by hydropower. About 10% of all the electricity in the United States is provided by hydropower. Hydropower generating prevents a lot of pollution. Hydropower generating is clean and does not leave any waste. Because of the electricity generated by hydropower, the amount of oil and coal needed to produce enough electricity is reduced. It prevents the need to burn about 22 billion gallons of oil or 120 million tons of coal each year.
The amount of electricity that a hydroelectric plant produces depends on two things: how far the water falls and the quantity of water falling. The higher the dam, the further the water falls and the more electric power produced. If the water falls twice as far, there will be twice as much electricity generated. The quantity of water that falls also affects the amount of power produced. The more water that flows through the turbines making them spin, the more electric power produced.
Water is also essential in industry. It is heated and the steam is used to run machinery. Water is used to cool hot metal such as in the production of steel.

Steel Factory Photo courtesy of FreeFoto.com

Water is also used to cool the air. It is an important element in many products like chemicals, drugs, lotions, shampoos, cosmetics, cleaners, and also beverages. Water is used in processing food and in innumerable factories and industrial processes including the manufacturing of paper. Water used in processing foods and beverages must be absolutely clean, while other industries such as a manufacturing plant may use a lower quality of water. "In the early 1900s, American industry used about 10 to 15 billion gallons of water a day. With the huge growth in industry following World War II, the industrial use of water also grew. By 1980, industry was using about 150-200 billion gallons each day." - Water: A Resource in Crisis by Eileen Lucas

Canoe Photo courtesy of BigFoto.com

Recreation is another way that we use and enjoy Washington state's water. Many people enjoy fishing, boating, sailing, canoeing, rafting, and swimming, as well as many other recreational activities that depend on water. Most of us enjoy at least one of these activities and would be disappointed if we could never do any of them again. If our water is continually polluted though, then it could become dangerous to go swimming and all of the fish could die so that no one could go fishing either. No one would enjoy boating, sailing, canoeing, or rafting in polluted water either. We need to remember that it is important to guard our waters from becoming polluted.

Transportation is yet another way that we use water. Many people use boats and ferries to commute to and from work every day. People also enjoy going on cruise ships or just going sailing. Water transportation has been a channel for growth in America, but that growth has not come without cost. The destruction caused by shipping includes fuel spills, which coat the water with oil and coal dust, and erosion of the shoreline which causes damage to the fish and other inhabitants of the water.

USES OF WATER

Water is the common name applied to the liquid form (state) of the hydrogen and oxygen compound H2O. Pure water is an odorless, tasteless, clear liquid. Water is one of nature's most important gifts to mankind. Essential to life, a person's survival depends on drinking water. Water is one of the most essential elements to good health -- it is necessary for the digestion and absorption of food; helps maintain proper muscle tone; supplies oxygen and nutrients to the cells; rids the body of wastes; and serves as a natural air conditioning system. Health officials emphasize the importance of drinking at least eight glasses of clean water each and every day to maintain good health.

Since water contains no calories and can serve as an appetite suppressant and helps the body metabolize stored fat, it may possibly be one of the most significant factors in losing weight. In his book, titled "The Snowbird Diet" Dr. Donald Robertson says the body will not function properly without enough water and discusses the importance of drinking plenty of water for permanent weight loss: "Drinking enough water is the best treatment for fluid retention; the overweight person needs more water than the thin one; water helps to maintain proper muscle tone; water can help relieve constipation; drinking water is essential to weight loss."

Water is a key component in determining the quality of our lives. Today, people are concerned about the quality of the water they drink. Although water covers more than 70% of the Earth, only 1% of the Earth's water is available as a source of drinking. Yet, our society continues to contaminate this precious resource. Water is known as a natural solvent. Before it reaches the consumer's tap, it comes into contact with many different substances, including organic and inorganic matter, chemicals, and other contaminants. Many public water systems treat water with chlorine to destroy disease-producing contaminants that may be present in the water. Although disinfection is an important step in the treatment of potable water, the taste and odor of chlorine is objectionable. And, the disinfectants that are used to prevent disease can create byproducts which may pose significant health risks. Today, drinking water treatment at the point-of-use is no longer a luxury, it is a necessity! Consumers are taking matters into their own hands and are now determining the quality of the water they and their families will drink by installing a drinking water system that will give them clean, refreshing, and healthier water.

Properties: The freezing point of water is 0° C (32° F), and its boiling point is 100° C (212° F). Water reaches its maximum density at 4° C (39° F) and expands upon freezing. Water combines with salts to form hydrates and reacts with metal oxides to form acids (see Acids and Bases).

Occurrence: Water is the only substance that occurs at ordinary temperatures in all three states of matter: solid, liquid, and gas. As a solid, ice, it forms glaciers, frozen lakes and rivers, snow, hail, and frost. It is liquid as rain and dew, and it covers three-quarters of the earth's surface in swamps, lakes, rivers, and oceans. Water also occurs in the soil and beneath the earth's surface as a vast groundwater reservoir. As gas, or water vapor, it occurs as fog, steam, and clouds.

 

Water in Life: Water makes up 50 to 90 percent of the weight of living things. Protoplasm is a solution of water and fats, carbohydrates, proteins, and salts. Water transports, combines, and chemically breaks down these substances. Water also aids the metabolic breakdown of proteins and carbohydrates.

Natural Water Cycle: The continuous movement of water between the earth and the atmosphere is the hydrological cycle. Water vapor from water and land surfaces and from living cells circulates through the atmosphere and falls as rain or snow. When it reaches the earth, water either flows into streams and then into oceans or lakes, or it enters, or infiltrates the soil. Some water becomes soil moisture, which may evaporate directly or move up through the roots of plants and be released by leaves. Some water percolates downward, accumulating in the so-called zone of saturation to form the groundwater reservoir, the upper surface of which is the water table. Under natural conditions, the water table rises in response to inflowing water and then declines as water drains into natural outlets such as wells and springs.

Composition: Because water dissolves numerous substances in large amounts, pure water rarely occurs in nature. Precipitation absorbs carbon dioxide and other gases, as well as traces of organic and inorganic material from the atmosphere. Because water reacts with minerals in the soil and rocks, surface and groundwater may contain many different dissolved substances. Surface waters may also contain domestic sewage and industrial wastes. Groundwater from shallow wells may contain nitrogen compounds and chlorides, but water from deep wells generally contains only dissolved minerals. Seawater contains many soluble compounds in addition to salt.

Water Purification: Impurities are removed from water by screening, sedimentation, filtration, chlorination, or irradiation. See also Sewage Disposal. Aeration saturates water with air, usually by spraying fountains of water into the air. Aeration removes odors and tastes caused by decomposing organic matter, industrial wastes, and some gases. Various salts and metals cause hardness in water. Hardness may be removed by boiling, by adding sodium carbonate and lime, or by filtering through natural or artificial zeolites.

Water Desalinization: Three desalinization processes, which involve evaporating salt water and then condensing the resulting steam, are known as multiple-effect evaporation, vapor-compression distillation, and flash evaporation. Freezing is another desalinization method, based on the different freezing points of fresh and salt water. Ice crystals are separated from the salt brine, washed, and melted into fresh water. In reverse osmosis, pressure forces fresh water through a membrane that does not allow minerals to pass. In electrodialysis, the positive and negative ions of the dissolved salt are removed from water by an electric current through special membranes.

These fine drinking water systems reduce a wide range of contaminants of health concern for a low cost per gallon. The superior effectiveness of solid carbon block systems is confirmed by testing and certification by NSF International; independent laboratory tests; certification by the State of California Department of Health Services; and more importantly, by the more than two million satisfied customers throughout the world. The performance of the solid carbon block filter technology exceeds that of all other filter types and meets only the highest standards for quality.