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Senior High School Lesson Plans

by Leslie Comnes, M.A.

School Water Audit

Students examine their school's water use, and make suggestions for conserving water at school.

Subjects:

Math, Science, Social Science

Materials:
  • stop watches
  • measuring vessels (gallon or gallon)
  • paper
  • clipboardsor other hard writing surfaces
  • copy of the school's water bill, if possible
Background Information:

Earth often is called the "water planet" because oceans or ice fields cover nearly three quarters of its surface. This abundance might make water seem an unlimited resource. Yet, less than one-hundredth of one percent of the earth's water, less than one cup-full out of every ten thousand cups, falls upon the land each year as fresh water. Less than two-thirds of one percent of Earth's water resides underground, much of it too deep or too brackish to be useful and little of it replenished as fast as it is pumped to the surface. Water good enough to drink, to farm with, to use in factories, or to share with lake and river life, is a rare and precious substance on this most watery of planets in our solar system.

To urban dwellers, water seems particularly abundant because it is nearly effortless to come by: just turn on the faucet and out it pours. The convenience of pressurized plumbing makes it easy to overuse water without thinking about the consequences. Most of our water consumption results from cultural and economic habit, a part of the way we live. Physically, the active adult human body requires only about a gallon of drinking water per day to maintain health in a moderate climate. Culturally, we average about 125-150 gallons per day domestically in the United States, per person, most of this for washing, flushing, and watering. While drinking less water than we need for our health is a bad idea, using more water than we need for our residential purposes is a bad habit. We could get the same jobs done using half as much. Improving the efficiency of our water use will provide water to share with all the diverse demands on this limited resource.

In the western states where the climate is dry, the necessity of water for human activities has been inscribed upon the land with public works. Here, people rely on extensive (and expensive) systems of dams and diversions to deliver fresh water from where and when it occurs naturally, to where and when it is used by people. In California, for example, most of the fresh water collects in the Sierra Nevada mountains as winter snow pack; a network of reservoirs, aqueducts, and pipelines regulates and transports the Sierra runoff hundreds of miles to metropolitan areas demanding far more water year-around than local sources can supply. For Los Angeles, the reach for water extends across the Mojave Desert, up the Colorado River, to the Rocky Mountains a thousand miles and four states away.

In the West, rapid population increases throughout a relatively recent history of urbanization have continually strained these distant water supplies, leading to successive waves of waterworks construction. Finally, however, we are approaching the limits of availability. During extended periods of below-average rainfall when many of the region's reservoirs and underground aquifers seem in danger of being drained dry, water conservation becomes a common, even required, practice. With a growing population has come a growing realization that useable water is in finite supply, and that nature itself needs water for ecological health. We have only so much, and we have to share it.

By following a few straightforward water conservation steps, a typical family of four can save 50,000 to 100,000 gallons of water a year. Outdoor purposes account for two thirds of the water consumed by suburban households during summer's heat. Simple measures can save thousands of gallons a month: watering in the morning to reduce evaporation, watering lawns no more than what the climate requires, maintaining turf sprinkling systems, leveling turf areas, landscaping with low-water plants, sweeping instead of hosing driveways, and turning off the hose between rinses when washing the car.

Conserved water is the most cost effective, environmentally benign source of "new" water. WaterShare means there will be water to share with all, when we all practice water management care.

Sources:

California Water Issues. Sacramento, CA : Water Education Foundation, 1997. Fact Sheet: 21 Water Conservation Measures for Everybody.

Washington, DC: Environmental Protection Agency, Office of Water.

Layperson's Guide to Water Conservation. Sacramento, CA: Water Education Foundation, 1997.

Water, by Luna Leopold, Life Science Library, 1966

Preparation:

Inform the appropriate school personnel (principal, custodian, gardener, for example) of the students' upcoming research. Obtain a copy of the school's water bill.

 

Questions for discussion:

Responses to seek:

Why do you think we should be concerned about saving water?

Concept of managing for multiple uses

What are some of the water saving methods you learned about at the WaterShare web site?

Concept of generalizing from individual behavior to group and institutional behavior

Do you think these methods could be used in our school?

Concept of persuasion, consensus building

How many gallons of water do you think our school uses in a month? (If possible, show students the school's water bill.)

Concept of institutional water management

How could we explore ways to reduce our school's water use? Concept of change management
Procedure:

Divide the class into six or seven groups. Explain that each group will be responsible for collecting data about a certain aspect of the school's water use. (You can adapt the groups' research depending on your class and on your school's situation.)

Classroom Sinks Group
This group will exmine the water use in classroom sinks, and estimate the total classroom sink use in an average month. They might measure the flow rate of several science, art, and shop class sinks (how many gallons of water flow in a minute), then take an average. They might time the average length teachers and students keep the water running while in these classes, and ask teachers about sink use.
Restroom Sinks Group
This group will examine the water use in restroom sinks, and estimate the total sink water use in an average month. They might determine the flow rate of a typical sink (how many gallons of water flow in a minute). They might then time the average length students keep the water running while washing their hands in the restrooms, and tally the number of students who use the sinks over a certain length of time.
Water Fountains Group
This group will examine the water use in water fountains, and estimate the amount of water used in a month. They might measure the flow rate of a typical fountain (how many gallons of water flow in a minute, for example), count the number of students that take a drink in an typical day, and time how long the fountain is kept running per drink, calculating an average.
Cafeteria Group
This group will examine the water use in the cafeteria, and estimate the amount of water used for food preparation and clean-up in a month. They might measure the flow rate of cafeteria sinks (how many gallons of water flow in a minute, for example), and time the number of minutes the sinks are left running during the preparation and clean-up of a typical lunch. They might look for information about how much water the dishwashers use each cycle, and count the number of cycles used for a lunch.
Shower Group
This group will examine the water use in the gym showers, and estimate the amount of water used in a month. The group must be willing to conduct this investigation in ways that won't embarrass themselves or others. Group members might time their own gym showers and average the group's shower length. They might then ask gym teachers for the number of students who shower in a typical day, and do the calculation to estimate a month's water use. They might determine the flow rate of the showers by measuring (when other students aren't there) the amount of water that flows in a minute from several different showers, then averaging. (An average home shower uses about 6 gallons per minute; and low-flow shower heads use about 2.4 gallons per minute).
Restroom Group
This group will examine the water use in the school restroom toilets. The group must be willing to conduct this investigation in ways that won't embarrass themselves or others. Each group member might tally the number of times he or she flushed the toilet at school over a typical day, then average the group's use. They could then multiply this average by the number of students at the school to estimate the number of flushes. They might ask school personnel about the average water flow per flush (an average toilet uses 7 gallons per flush, while low-flow ones use as low as 2 gallons).
Landscaping Group
This group will examine the water use for the school's landscaping, and estimate the amount of water used to care for the landscaping in a typical month. Students might talk with school or district personnel in charge of the landscaping to learn about how and how often the plants are watered, and about the types of plants. Students can determine the flow rate of the hoses or other water devices by measuring the gallons of water flow in a minute. Students might research plants that could grow in your area with less watering.

After the investigations, ask the groups to share what they have learned with the rest of the class. Make a class chart showing the monthly average water uses students estimated. Compare the class estimate with the school's water bill. What might account for any differences?

Ask each group to suggest ways that the school could conserve water in the area they researched. As a class, choose several ways the school as a whole could conserve water.

Follow-Up:

Help students implement some of their ideas for conserving water at school. For example, they might put signs up at sinks or at water fountains encouraging fellow students to not waste water, or they might advocate that the administration plant drought-tolerant shrubs to replace water guzzling plants. Afterwards, students can monitor the water usage to see the effect of their efforts.

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