Our World of Water

Water Use and Conservation

The United States as a whole receives an average of about 30 inches of precipitation annually. In other words, the annual rainfall would cover the whole country to a uniform depth of 2½ feet. Almost three-fourths of this water is returned to the atmosphere by evaporation and transpiration. The remaining one-fourth contributes to runoff and ground water storage and makes up the water available for use.

Water used for normal household purposes such as bathing, dishwashing, and toilet flushing is not consumed. Most of it is returned to the hydrologic cycle through your sewer system. How water probably is used in your home is shown by the following charts. Consider an average household in Minnesota. If you are like the majority of Minnesotans, here are some typical amounts that you would use:

These figures average at about 50 gallons per person per day. If you live on a farm, the daily use of water by farm animals is added to your family's need.

The crops grown on your farm also require a tremendous amount of water. To understand how much water certain crops need, here is a list of what each plant needs during one growing season (6 to 7 months):

Even an undesirable plant like ragweed requires 140 gallons of water during the summer. The water for crops comes from soil moisture, precipitation, or irrigation. Irrigation is becoming increasingly important in Minnesota. According to the Minnesota Department of Agriculture, in 1970 4.5 billion gallons of water were used for irrigation. By 1976 this figure had grown to 8.6 billion gallons and is still rising.

In addition to these uses, industry requires a great amount of water. In fact, industry is the largest user of water from municipal water supplies. In order to supply us with their goods and services, average use by commerce and industry is about 70 gallons per person per day. Besides domestic and industrial uses, there are two other main classes of municipal water use. The first is called public use, which includes fire extinguishing, street cleaning, public building use, and maintenance of public parks. Public use accounts for about 10 gallons per person per day. The other class of water consumption is loss or unaccounted-for waste. Leaks from water mains, unmeasured leaks from faucets, and errors of measurement contribute to this loss.

Though many industries buy water from the public or municipal supply, many large factories put in their own wells or surface reservoirs. If you live in the city or an area with a high concentration of people, you probably get your water from the municipal water system. These systems draw their water either from aquifers or surface reservoirs. If you live in the country, you probably get your water from your own well. Have you ever noticed the difference in taste between your water and other water? Why is this?

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Produced by Communication and Educational Technology Services, University of Minnesota Extension.

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