Water Conservation (At Home)
Grade Levels: Middle School,High School
Water usage and conservation is an important issue. Only 1 percent of the total water supply on Earth is available for humans. Of that, 42 percent is used in agriculture. Not all freshwater resources are evenly distributed. In Kansas, water usage and water rights are very important topics. As a state, how do we balance the need for water in agriculture, manufacturing, and our daily lives? It is important that everybody does their part to conserve the invaluable natural resource.
Teaching the Lesson
- Learning Objectives
- Lab #1: Demonstration of the amount of fresh water on Earth
- Lab #2: Calculating Flow Rate
Water covers three-quarters of the Earth’s surface. Over 97 percent of the earth’s water is found in the oceans as salt water. Only 3 percent of Earth’s water is freshwater. Of that, only 3 percent of it is usable freshwater available for human use. About 2 percent of the Earth’s freshwater is stored in glaciers, ice caps, and snowy mountain ranges. This leaves only 1 percent of the Earth’s water for our water supply needs. Freshwater supplies are found in the atmosphere, beneath the ground, or on the surfaces in lakes, rivers, and streams.
We use freshwater for a variety of purposes. According to the U.S. Environmental Protection Agency, agriculture represents the largest consumer use of fresh water at about 42 percent. Approximately 39 percent of our freshwater is used to produce electricity. About 11 percent of available freshwater is used in homes and businesses. The remaining 8 percent is used in manufacturing and mining.
The total amount of water on the planet does not change. Water moves around on the planet and changes form, but we will never have any more water than we have right now. With our growing population and ever increasing
demand on our freshwater supply, it is more important than ever that we learn to conserve the limited freshwater supply.
Lab #1: Demonstration of the amount of fresh water on Earth
- Measure 1 quart, or 32 oz, of water. Add a couple drops of food coloring so the water will be easier to see. This represents all the water on planet Earth.
- Measure out 1 oz or 6 teaspoons of water into a separate plastic cup. Label this cup “fresh water”. This water represents the fresh water on Earth available for humans, plants and animals to use. The 31 oz of water remaining in the quart jar is water found in our oceans.
- Using the 1 oz, or 6 tsp, of fresh water in your plastic cup, remove 5 teaspoons and put them into a new plastic cup labeled “frozen”. This water represents the amount of fresh water that is frozen in the ice caps, glaciers, and mountain tops. This water is unavailable for human use.
- From the 1 tsp of water that is left of your freshwater supply, measure out ¼ tsp and pour it into a separate plastic cup and label it “underground”. This represents the amount of fresh water that is found underground. Most of this is unavailable for human use.
- From the ¾ teaspoon of water left in your cup labeled “fresh water” that is left, use a pipette/ medicine dropper to extract 1 drop and place it in a plastic cup labeled “atmosphere”. This represents the amount of fresh water in the atmosphere. This is also unavailable for human use. The remaining 2 drops of water represent the Earth’s surface water. This is the amount of water that is found in our lakes, rivers and streams.
- From the remaining freshwater, use a pipette/medicine dropper to extract 1 drop and squeeze into a separate plastic cup labeled “polluted”. This represents the amount of fresh water that is too polluted for human use.
- Pour the remaining fresh water into the last plastic cup labeled “for human use”. This last drop is the surface water that is available for human use. From that last drop, 42 percent is used for agriculture, 39 percent is used to produce electricity, 8 percent is used in manufacturing and mining and 11 percent is used in homes and businesses.
Lab #2: Calculating Flow Rate
Tell students that we are going to try to come up with an estimate for how much water we use during the day. In order to do this, we need to practice calculating flow rate.
Gather six empty gallon milk jugs or 2-L bottles. Puncture a small hole in the bottom of each jug/bottle. Vary the size of each hole so the water will flow out at different rates. Label the bottles 1-6 with number one having the smallest hole and number 6 having the largest. Flows should range from slow drips to a steady stream. Cover the holes with tape. Fill the jugs about half full of water. Mark a line on the jug so that it can be refilled to the same point each time.
Using the jugs/bottles you prepared, a timer, a bowl and measuring cups do the following:
- Starting with bottle #1, hold the bottle above the bowl (preferably outdoors or in the kitchen sink). Remove the tape and start the timer.
- After 1 minute, student(s) should place their finger over the hole on the bottom of the jug to stop the water. Hold the jug over the sink. Tilt the jug to the side so the tape can be replaced. Refill the jug to the line marked on the side of the container.
- Use a measuring cup to measure the water that was collected. The amount of water collected is labeled ml/min. This can be converted to L/min. by dividing by 1,000 (your measuring cup may not have ml; in that case you would have oz/min.).
- Student(s) can measure the flow rate of their kitchen sink by timing how long it takes for a quart jar to fill. Divide 946 (1 quart = 946 ml) by your time. The answer will be in ml/sec. This can be converted to ml/min.
by dividing the answer by 60. And converted to L/min. by further dividing it by 1,000.
- This method can used to find the flow rate of drinking fountains, or any other water source in their home such as bathroom sink, bathtub, outside water hydrant. Use cups as needed.
- Next, we will try to find the flow rate for your shower and bath at home. Students can cut the top off one of the bottles/jugs you have numbered 2-6. Fill the bottle/jug with quart of water and mark the line on the outside. Then time how long it takes to fill up 1 quart of water.
- One toilet flush uses 5 gal. of water.
- A 10-minute shower uses 100 gal. of water.
- To fill half a bathtub takes 50 gal. of water.
- Brushing teeth takes 2 gal. of water.
- The dishwasher uses 10 gal. of water.
- The clothes washer uses 50 gal. of water
- On average, each of us uses about 70 gal. of water every day. Using the above information, students can calculate their daily water use. They can use their own data collected to figure out how much their shower uses. They can look up their dishwasher and/or washing machine to see how much water they use. Students can also use the above estimates if they cannot find the information they need. Fun fact: In pioneer days, it is estimated that people used only 5 gal. of water per day.
- Look for places in your day where you can reduce water use. Examples might include shorter showers, making sure the dishwasher if full before running it, turning off the water while brushing their teeth, etc.
This lesson is the work product of the Kansas Corn Commission. Our lessons are written in collaboration with Kansas teachers for use in the classroom. Teachers may copy and share this curriculum. Use of this product for commercial or promotional use is prohibited without express permission of Kansas Corn.