UGA College of Family and Consumer Sciences Cooperative Extension Service
Understanding the Water System

Dale Dorman, MS
Extension Housing & Environment Specialist,
Department of Housing and Consumer Economics

Document Use:

Water is critical to each of our lives. No other single substance is as important for our health, our economy or our way of life. For example:

  • People can live for weeks without food but only five to 10 days without water. Two quarts of water a day is required to help digest food, lubricate joints, clean eyes, remove body wastes and cool the body.
  • A dairy cow requires 3 gallons of water to produce 1 gallon of milk.
  • To grow an ear of corn requires 25 gallons of water.
  • A fast food meal of a hamburger, french fries and soft drink requires 1,400 gallons.
  • To manufacture one car requires more than 100,000 gallons of water.
No matter where we turn, water is important to our lives. Agriculture requires water for animals and plants to grow. Industry uses water in cleaning and processing, for transportation and in generating electricity. Consumers require water for health, hygiene, cooking and recreation.

Georgia has 4,000 miles of major rivers throughout the state; reservoirs and lakes cover more than 400,000 acres. Groundwater is also an important resource. In Georgia, 51 percent of the total water used comes from a surface water source; 49 percent comes from groundwater. The primary source for public water systems is surface water (70 percent); primary source for rural users is groundwater (90 percent).

Increasingly, Georgia's water resources are threatened by landfills and dumps, septic tanks, urban run-off and by agricultural and industrial operations. Shortages and incidents of contamination remind us that water must be conserved and protected. Clean and abundant water is a limited resource that can disappear if we do not manage it properly. Each of us has a responsibility to protect the water supply. Consumers, farmers and industries would suffer if the water supply's quality and quantity deteriorate. This publication discusses the basic issues in water quality to help you understand how to protect and conserve water sources for yourself, your community and your country.

Renewable But Limited Resource

The water we drink today is the same water that was used millions of years ago. It has remained almost unchanged in amount and in character ever since the earth was formed. Water is maintained in three states - as a liquid, gas or solid - and is constantly recycled. This unending circulation of the earth's water is called the hydrologic cycle . It is nature's purification system. However, as water moves over and through the earth's surface it is highly vulnerable to contamination. To protect our water supply, we must understand each process in the cycle and conditions that influence its quality.

Although water is in constant motion, it seems to be stored in oceans, lakes, reservoirs, rivers and in underground supplies. These sources are commonly referred to as surface water and groundwater.

Water in surface areas is heated by the sun; it then evaporates and turns into a gas. As moisture-laden air rises and cools down, it condenses in the atmosphere and forms clouds. Eventually it returns to earth as precipitation in the form of rain, snow, hail or sleet.

As precipitation falls, some of it evaporates directly into the atmosphere or is intercepted by vegetation. The remainder reaches the ground where it enters the soil by a process called infiltration. Precipitation continues to enter the soil until the rate it is falling is more than the soil will accept. Excess water then begins to fill surface depressions and flow over the soil surface. This overland flow of water is called surface run-off.

Part of the water that enters the soil is extracted by plants. Plants utilize some of the water and return the rest to the atmosphere by a process called transpiration.

Under the force of gravity, the remaining water percolates down and through the soil. How fast water can travel through the soil depends on the soil itself. Materials that allow water to pass through are permeable. Because sandy soils are permeable, water travels quickly, but clay soils do not let water move that fast. The extremely small size of the openings between microscopic clay particles create friction that effectively halts water movement. Saturated clay is virtually impermeable.

The Hydrologic Cycle

As water travels through the soil it passes through the zone of aeration. This may also be referred to as the unsaturated zone. This region may be moist, but the pores are only partly filled with water. As water continues down through the soil it eventually reaches a zone where all the interconnected openings are filled with water, the saturated zone. The top of the saturated zone is called the water table. The water table rises and falls according to the season of the year and the amount of precipitation.

A water-bearing soil or rock formation that is capable of yielding usable amounts of water is called an aquifer. Some aquifers are confined by layers of soil or rock which do not allow water to flow freely. These are referred to as confined or artesian aquifers. Aquifers that are not confined are commonly known as water table aquifers.

Aquifers represent major fresh water resources throughout the country. They may cover only a few miles in overall area or they may extend over hundreds of square miles. In Georgia, the four major aquifers are the Floridan, Claiborne, Clayton and Cretaceous.

The unsaturated and saturated zones and water table Confined or Artesian Aquifer Unconfined or water table aquifer

The Floridan aquifer is made of confined limestone, dolostone and calcareous sand. It supplies about 50 percent of the state's groundwater; its major users include Savannah, Brunswick, St. Mary, Albany and the Dougherty Plain area. The Claiborne and Clayton aquifers consist of confined sand and limestone. They are the major sources of water for southwestern Georgia. The Cretaceous aquifer, a system of sand and gravel, is the major source of water in east central Georgia.

Movement of Ground Water

Surface areas that allow water to percolate into an aquifer are called recharge areas. These areas may occupy only a very small area or extend over many square miles. In addition to the precipitation that falls directly onto the land surface overlying the aquifer, recharge may also be the result of run-off or streams that flow down from hillsides. Groundwater leaves the ground at discharge points. These points typically occur as seepage into wetlands, lakes and streams.

Groundwater moves slowly from aquifer to aquifer and from recharge area to discharge point. Depending on the geology of underground sediments, groundwater may move from a fraction of an inch to a few feet per day. For example, it can travel very quickly in porous and permeable materials such as gravel or limestone. However, in most cases, the water within aquifers moves at an extremely slow rate.

Aquifers are not exposed to air or sunlight, nor do they have the free-flowing, self-oxygenating, cleansing properties of surface waters. Because of these conditions, when groundwater contamination occurs, the concentration (plume) of pollutants moves slowly with little dilution or dispersion. By the time a plume reaches a well site it may be difficult to tell where it came from, when it was released into the groundwater and how long it will affect the well site.

Recharge area Discharge points

"Unconfined" aquifers are the most susceptible to contamination. These aquifers usually occur fairly close to the land surface and are not protected by an overlying layer of impermeable material. By contrast, "confined" aquifers are bounded on top and bottom by layers of relatively impermeable materials. They generally occur at greater depths and their impermeable layers offer a measure of protection from contamination. However, confined aquifers are vulnerable to contamination from their recharge area.

Groundwater movement is also affected by the contour of the surface land (topography). Groundwater tends to follow the land's contour unless it encounters barriers, like impermeable layers of rock. For example, groundwater will move toward the bottom of a hill. Anything entering the groundwater on the top of a hill will generally find its way down to the bottom. That is why it is important to locate a septic tank away from, and at a lower point, than a well.

What Affects Groundwater?

Many types of human activity can affect the quantity and quality of water in an aquifer. For example, too much pumping from wells can deplete an aquifer faster than it can be recharged. This leads to a decline in water levels which can extend to other areas served by the same aquifers. Constructing buildings, paving roads and parking lots, diverting streams and draining wetlands can affect recharge to an aquifer and limit its ability to replenish itself.

Sources of Groundwater Contamination

The lowering of the water table in an aquifer can make the aquifer vulnerable to encroachment from outside bodies of water. This can be disastrous if the entering waters are saline or polluted. Concentrations of salts, minerals and other materials may increase to a level at which the aquifer is unsuitable for certain uses such as drinking or irrigation.

Groundwater quality can be affected by the improper use and disposal of toxic chemicals. These substances can be carried into surface water supplies by run-off, or they may leach through the soil into groundwater.

Contaminating the Water Supply

Because water is a natural resource, it must be managed properly to protect it for future generations. One of the greatest threats to the water supply is contamination from pollutants. Because water is a natural solvent, it can carry minerals and chemicals, some of which may be harmful to humans.

In the past, the biggest threat to water supplies was microorganisms which caused diseases like dysentery, typhoid and giardiasis. While these diseases are still present to a small degree, today the larger issue for water quality comes from contamination by organic and inorganic chemicals. Inorganic chemicals include metals and nutrients, while organics include pesticides and industrial solvents. Many of these chemicals have been linked to cancer, liver and kidney disease, and nervous system damage.

A major difficulty in identifying contaminants is knowing their source. Point sources are those that can be readily identified, like wastewater from sewage treatment or a manufacturing plant. Point sources of pollution have decreased in recent years because of federal and state laws. Enforcement of these laws tends to be straight-forward because the source of pollution can be determined.

A second major source of pollutants is nonpoint sources. Nonpoint sources are scattered over a large geographic area and come from a variety of places. These include sediments, animal wastes, pesticides and other materials carried by water from agriculture, municipal dumps and run-off. With nonpoint pollution, identifying a single responsible polluter is more difficult because it can come from a variety of sources. Regulation is less effective and tends to rely on voluntary compliance.

Where do the chemical contaminants come from? A variety of sources -- industries, agriculture, municipalities and individuals.

Industry

In the past, the media have focused most closely on pollution from industrial wastes and their by-products. Extractive industries, like mining and forestry, produce acid mine drainage, brine and soil erosion. Although legislation has reduced the impact of these industries, by-products still pollute the water supply.

Manufacturing industries often use toxic chemicals during production. Proper disposal of these chemicals can be very costly, and the temptation is great to dump them illegally. Even legal disposal of industrial by-products in landfills and toxic dump sites can cause problems. Over time, regulators have found that even the best prepared sites can leak harmful chemicals into the groundwater.

Agriculture

Another source of pollution of water supplies is from agriculture. A farm operation may use many pesticides and fertilizers in producing a crop. If improperly applied, these chemicals can percolate through to the groundwater. Animal wastes can also contaminate the water supply, particularly in feedlots where a large number of animals are kept in a relatively small area. Unless the wastes are dispersed over a large area or stored in a contained lagoon, ground and surface waters can be contaminated from run-off. Another agricultural contaminant is excessive soil erosion which clogs rivers and streams.

Municipalities

Cities and towns also contribute to water quality problems in many ways. Contaminants can leach from municipal landfills as rain filters through the solid wastes and percolates into the ground. Sewage treatment plants produce sludge which contains heavy metals and organic chemicals. The sludge is often spread over soil and can find its way into the groundwater. Urban runoff from roads, parking lots and storm sewers can also contribute to water pollution as it picks up chemicals, soil, trash and oil products. Municipalities also use pesticides and herbicides in parks, golf courses and along roads to control pests and weeds. These chemicals also find their way to the groundwater.

Finally, commercial activities in cities and towns contribute to water quality problems. Many businesses use chemicals as sales products, in processing and as cleaning agents. One particularly important problem is storage tanks, either above or below the ground, which can leak chemicals into the groundwater.

Individuals

A final source of water pollution is individuals. Within the home a number of toxic chemicals are used for cleaning, painting and car care. Often people do not consider the potential damage to ground and surface water when they dispose of these chemicals in the sink, toilet or trash. About 25 percent of all homes use septic systems for sewage disposal. These systems can leach harmful chemicals into the groundwater, particularly if they are poorly constructed or maintained. Homeowners also use lawn and garden products which can get into the ground or surface water.

What Can Be Done?

Most of the problems of water quality and quantity can be managed provided industries, farmers and consumers are committed. Technology and knowledge are available. The question is, Are we willing to make the changes and sacrifices needed to protect the water supply? Here are some suggestions.

Industry

Since the Water Pollution Control Act of 1972, industries have greatly reduced their pollution of the nation's surface waters. However, some violations continue. Industries can improve their record by conserving water, treating and reusing water in production and reducing their use of toxic chemicals. These simple methods can go a long way toward improving the water system.

Agriculture

Many methods can help farmers protect both surface water and groundwater as well as the environment in general. These methods are commonly referred to as Best Management Practices (BMPs). Here are a few examples:

  • cropping and tillage practices that minimize soil erosion
  • Integrated Pest Management (IPM)
  • applying chemicals according to label recommendations, but only when needed
  • proper irrigation scheduling to prevent run-off and leaching
  • well-head protection
  • using animal waste products for fertilizer, feed or other appropriate uses
  • nutrient management for crop land
Federal programs are already in place that encourage the adoption of many of these practices.

In Georgia, agricultural water users are required to have a permit if they withdraw more than 100,000 gallons per day in any one month. This regulation applies to withdrawals from either groundwater or surface water sources. This permit requirement will allow the state to monitor agricultural water uses and consequently to manage the state's water resources as a whole.

Municipalities

Many water systems in cities and towns could benefit from increased maintenance of existing facilities, like the treatment plant or the pipe distribution system. In many systems leakage through underground pipes can be 30 percent or more of the flow. In Georgia, regulations to encourage conservation are being adopted. For example, municipal water systems are now required to account for "lost" water (water that leaks from the distribution system, also unmetered water) and to have a long-term, demand-reduction water conservation plan in place before a permit will be granted to increase withdrawal from a water source.

Finally, municipalities can work with local businesses to guard against threats from the improper disposal of chemicals and leaky storage tanks.

Individuals

Although individuals are not the largest water users, they can make an impact on conserving water and improving quality. Most homes could easily reduce water consumption by 20 percent or more by using low-flush toilets, low-flow faucets and showerheads. Even larger savings could be made by conserving while watering lawns and washing cars. Recent legislation has been passed in Georgia requiring the use of water-saving plumbing fixtures in all new construction. The law also applies to remodeling projects that involve the installation of plumbing. This legislation is especially important in high growth areas where water demand has risen so drastically. To help protect water quality, people can practice safe methods for the use and disposal of household chemicals and automobile oil.

Most important, however, is to foster a climate of understanding and concern. Too many people are part of the "hydro-il-logical" cycle. When problems arise over quality or quantity there is great concern. Once problems diminish, however, apathy returns. Our present reactive approach to water issues needs to shift toward a proactive stance. Until people are aware of water's importance on a continuous basis, present conditions will get worse. Georgia cannot afford to squander this precious resource.

References

Drinking Water: A Community Action Guide. Concern, Inc. Washington, D.C., 1986.

Groundwater: A Community Action Guide. Concern, Inc. Washington, D.C., 1988.

Gaber, Ramond, Is Your Water Safe to Drink? Consumers Union, Mt. Vernon. N.Y., 1988.

Hodler, T.W., H.A. Schretter, The Georgia Atlas. Institute of Community and Area Development. The University of Georgia, Athens, GA., 1986.

Partial funding for this publication was provided by the Georgia Department of Agriculture and the U.S. Environmental Protection Agency.
Special appreciation to Linda Heaton, Clothing and Textiles Specialist; Tom Ilvento, Community Development Specialist; Joe Taraba, Agricultural Engineering Specialist, University of Kentucky Cooperative Extension Service, for the use of their original material.
The University of Georgia and Ft. Valley State College, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.

An Equal Opportunity Employer/Affirmative Action Organization Committed to a Diverse Work Force
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.

Gale A. Buchanan, Dean and Director
Document use:
Permission is granted to reproduce these materials in whole or in part for educational purposes only (not for profit beyond the cost of reproduction) provided that the author and the University of Georgia receive acknowledgement and the notice is included:

Reprinted with permission from the University of Georgia.
Dorman, D. (1996). Understanding the Water System. Athens, GA: University of Georgia, Cooperative Extension Service.

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Content Person Contact: Jorge Atiles, Ph.D. jhatiles@fcs.uga.edu
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Document Review: level 3: State/Regional Peer Review
Document Size: 21k
Publication Date: 1996-03-01
Entry Date: 1997-08-01
Pull Date: 1999-08-01
Pub #: C819-7

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