The Connection Between Water Use and Energy Use: An Introduction

Transcription

1 The Connection Between Water Use and Energy Use: An Introduction INTRODUCTION Many people realize the importance of conserving water and conserving energy; however, there are many links between energy use and water use that are not directly obvious to consumers. In this lesson, students discover these connections by learning how sources of energy require substantial amounts of water and how energy is used in the process of providing tap water to millions of homes. They will also understand that a sustainable future requires us to use both of these resources very wisely and be able to name specific actions they can take to reduce their use of water and energy. LESSON OVERVIEW Grade Level & Subject: 9-12; Science, Math and Social Studies Length: 2-3 class periods Objectives: After completing this lesson, students will be able to: Identify a variety of ways in which energy is used during the process of transporting and treating the water that we use in our homes. Explain why water is used when we turn on a light or use energy for other activities. Name specific actions people can take to reduce their use of water and, thus, energy. Explain the pressures that a growing population will put on water sources and municipalities when we use more energy, and vice versa. National Standards Addressed: This lesson addresses the following National Science Education Standards from the National Academies of Science: Content Standard: NS SCIENCE AND TECHNOLOGY As a result of their activities, students should develop an understanding of: Abilities of technological design Understandings about science and technology Content Standard: NS PERSONAL AND SOCIAL PERSPECTIVES As a result of activities in grades 9-12, all students should develop understanding of Personal and community health Population growth National Resources Environmental quality

2 Natural and human-induced hazards Science and technology in local, national, and global challenges This lesson addresses the following Standards & Position Statement from the National Council for the Social Studies: Content Standard: NSS-G.K-12.5 ENVIRONMENT AND SOCIETY As a result of activities in grades K-12, all students should Understand how human actions modify the physical environment. Understand how physical systems affect human systems. Understand the changes that occur in the meaning, use, distribution, and importance of resources. This lesson addresses the following Standards for School Mathematics from the National Council of Teachers of Mathematics: Content Standard: NM MEASUREMENT STANDARD FOR GRADES 9 12 Instructional programs from prekindergarten through grade 12 should enable all students to Understand measurable attributes of objects and the units, systems, and processes of measurement. In grades 9 12 all students should Make decisions about units and scales that are appropriate for problem situations involving measurement. Content Standard: NM PROBLEM SOLVING STANDARD FOR GRADES 9 12 Instructional programs from prekindergarten through grade 12 should enable all students to Build new mathematical knowledge through problem solving; Solve problems that arise in mathematics and in other contexts; Apply and adapt a variety of appropriate strategies to solve problems; Monitor and reflect on the process of mathematical problem solving. Content Standard: NM CONNECTIONS STANDARD FOR GRADES 9 12 Instructional programs from prekindergarten through grade 12 should enable all students to recognize and apply mathematics in contexts outside of mathematics. Materials Needed: Reproducible #1 Discovering the Connections between Water Use and Energy Reproducible #2 Discovering the Connections between Water Use and Energy ANSWER KEY Reproducible #3 Cost-Effective Ways to Save Water at Home Reproducible #4 Discovering the Connections between Energy Use and Water Reproducible #5 Discovering the Connections between Energy Use and Water ANSWER KEY Reproducible #6 Information on Conducting a Household Water Audit Reproducible #7 Personal Water Audit Reproducible #8 Tracking Shower Time and Water Use Access to a computer with internet connection and a projector

3 Index cards or paper Access to computers with internet connections for student research (optional for Extension) Poster paper or exhibit boards (optional for Extension) Assessment: Students will be assessed through the following activities: Completion of Discovering the Connections between Water Use and Energy packet. Completion of Discovering the Connections between Energy Use and Water packet. Completion of water audit and participation in related discussion. Participation in a reflection exercise and class discussion about what they learned. LESSON BACKGROUND Relevant Vocabulary: Aqueduct: a conduit for water; a structure or hollow that transports water; often from a remote source and usually by gravity. 1 Embedded Energy: also known as Cumulative Energy Demand, represents the sum of all the energy inputs into a product system, from all stages of the life cycle (for example, extraction of materials, processing, transportation, manufacture, etc). 2 Fossil Fuels: hydrocarbons such as coal, oil, and natural gas that formed from the remains of dead plants and animals. 3 Gravity: the force of attraction between all masses in the universe, especially the attraction of bodies to Earth s surface. 4 Kilowatt Hour (kwh): the amount of energy that would be transferred at a constant rate of one kilowatt for one hour. 5 Megawatt (MW): a unit for measuring power that is equivalent to one million watts. 6 Nexus: a connection or link associating two or more items in a series. 7 Nuclear Energy: energy that is released through the process of fission, the splitting of atoms to release energy from the atomic nucleus; 8 power generated by a nuclear reactor or apparatus in which fissile material can be made to undergo a controlled, self-sustaining nuclear reaction releasing energy. 9 1 Aqueduct, Merriam-Webster. Retrrived 10 March 2010 from 2 Greening the Building Lifecycle, Department of the Environment and Heritage. Retrieved 10 March 2010 from 3 Fossil Fuel, Science Daily. Retrieved 10 March 2010 from 4 Gravity, WordNet Princeton. Retrived 10 March 2010 from 5 Kilowatt Hour, About.com. Retrieved 10 March 2010 from 6 Megawatt, About.com. Retrived 10 March 2010 from 7 Nexus, WordNet Princeton. Retrieved 10 March 2010 from 8 Nuclear Energy, WordNet Princeton. Retrieved 10 March 2010 from 9 Nuclear Power. Oxford English On line Dictionary. Retrieved 12 March 2010 from

4 Nuclear Fission: a nuclear reaction in which a large nucleus such as uranium is split, forming two smaller nuclei. This process releases energy and sometimes radioactive particles. 10 Population Growth Rate: annual percentage increase in the number of individuals in a given area. 11 Reservoir: a large store of a substance; an artificial lake or holding area where water is collected and kept in quantity for later use. 12 Septic System: underground sedimentation tank that holds sanitary waste and is typically comprised of a septic holding tank and subsurface fluid distribution or disposal system. 13 Ultraviolet Radiation: a water purification process that helps to kill bacteria and other micro-organisms. 14 Wastewater Treatment Plant: facility that removes pollutants from wastewater (or used water) through a series of tanks, screens, filters, and other processes. 15 Water Footprint: equal to the water required to produce the goods and services an individual consumes. 16 Water Treatment Plant: a facility that uses various processes to clean and purify water for drinking and it is required to meet national standards that meet the Clean Drinking Water Act. Watt: a unit of power equal to 1 joule per second; the power dissipated by a current of 1 ampere flowing across a resistance of 1 ohm. 17 Information: Many people have learned about the importance of conserving water and saving energy, but not many people understand that the use of these resources is intricately linked. The process of procuring fresh water from its original source and then transporting it to a water treatment plant and individual homes and back requires an enormous amount of energy. Water treatment facilities use energy to purify and disinfect the water before it goes to people s homes and businesses. Once the water leaves the treatment plant, it is often pumped to storage areas or reservoirs and pumped again to homes and businesses. Thus, the treatment and transportation of water uses significant amounts of energy. It is thought that 4% of the energy in the United States is dedicated to the treatment and 10 Nuclear Fission. About.com Physics. Retrieved 12 March 2010 from 11 Glossary, Department of Environmental Affairs and Tourism. Retrived 10 March 2010 from 12 Reservoir, Merriem-Webster. Retrieved 10 March 2010 from 13 Glossary, Utah Division of Water Quality. Retrieved 10 March 2010 from 14 Ultra Violet Radiation. Gleick, P.H. and Cooley, H.S. (2009). Energy Implications of Bottled Water. IOP Publishing ltd. UK. P Glossary, United Nations Environment Programme Division of Early Warning and Assessment and Global Resource Information Database. Retrived 10 March 2010 from 16 Introduction, Water Footprint. Retrieved 10 March 2010 from 17 Watt, WordNet Princeton. Retrieved 10 March 2010 from

5 transportation of water and wastewater, 18 with nearly 80% of that energy dedicated to moving water. 19 Similarly, water is required in large quantities to produce many of the sources of energy that we rely upon. For example, 39% of all freshwater withdrawals made in the United States is dedicated to the production of electricity through fossil fuels and nuclear power. 20 This means that many Americans may be using as much water to produce the electricity they use in their homes as the amount of water they directly use for showering, laundering, and cooking. Why is it important to understand the links between energy and water use? With a growing human population, there will be a greater demand for fresh water, which will require larger amounts of energy to treat and transport. It is estimated that by 2020 the United States will need to build well over a thousand new power plants to generate the energy required by an increasing population. 21 While the population is rising, the amount of fresh water is not. As fresh water levels decline, it may need to be pumped longer distances, which requires yet more energy. Similarly, a growing human population will require more energy to be produced, and energy production requires large amounts of fresh water. Further, the burning of more fossil fuels produces emissions that contribute to global climate change. A changing climate will likely affect the amount of rain and fresh water that is available in many areas of the world. Thus, the ability to provide clean and affordable water is inextricably linked to energy and vice versa. Resources: The Water-Energy Connection, National Environmental Education Week, Conserving Water Conserves Energy, EPA Water Quality Video Contest, Exploring the Energy-Water Nexus, National Renewable Energy Laboratory, Reduce Hot Water Use for Energy Savings, Energy Savers, U.S. Department of Energy, Saving Water Saves Energy, WaterSense, U.S. Environmental Protection Agency, Calculate Your Water Savings, WaterSense, U.S. Environmental Protection Agency, 18 Saving Water Saves Energy, WaterSense, U.S. Environmental Protection Agency, 19 Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p Exploring the Energy-Water Nexus: A Stakeholder Dialogue for Identification of Critical Issues, National Renewable Energy Lab, 21 Exploring the Energy-Water Nexus: A Stakeholder Dialogue for Identification of Critical Issues, National Renewable Energy Lab,

6 Benefits of Water Efficiency, WaterSense, U.S. Environmental Protection Agency, Shower Power, WaterSense Kids, U.S. Environmental Protection Agency, Energy Star Products, Energy Star, U.S. Department of Energy and U.S. Environmental Protection Agency, Energy and Water, Sustainable Infrastructure for Water & Wastewater, U.S. Environmental Protection Agency, Calculating Energy Needed to Heat Water, Sun Volt Solar, Formisano, Bob, How to Quickly Determine Your Faucet or Shower Flow Rate in GPM, Plumbing Repair, About.com, Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. Saving Water and Saving Energy, Waste Quality and Water Management, North Carolina Cooperative Extension Service, 15 Ways to Save on Your Water Heating Bill, Energy Savers Blog, U.S. Department of Energy, Heating-Bill.aspx. U.S. EPA WaterSense Calculator LESSON STEPS Warm-Up: PSA on Energy and Water 1. Begin the lesson by showing a thirty second public service announcement that earned Honorable Mention in the U.S. EPA's 2009 Water Quality Video Contest. It illustrates the connection between water and energy consumption. Find this public service announcement, Conserving Water Conserves Energy, on YouTube at this address: While this PA announcement does not explain the connection between energy and water, it is simple and provocative and will act as an excellent introduction to this lesson. 2. Ask your students if they knew that letting their faucet run for five minutes uses about as much energy as letting a 60-watt light bulb run for 14 hours? 22 Why might this be? Because water is required in large quantities to produce many of the sources of energy that we rely upon. For example, 22 Benefits of Water Efficiency, WaterSense. U.S. Environmental Protection Agency,

7 39% of all freshwater withdrawals made in the United States is dedicated to the production of electricity through fossil fuels and nuclear power Explain to your students that they will be exploring this little-understood relationship between water and energy. Activity One: Linking Water Use and Energy 1. Pass out copies of Reproducible #1 Discovering the Connections between Water Use and Energy. Ask students to work in pairs or small groups. Touch base with the students as they work through the sheet, clarifying and discussing any questions they may have. 2. As students arrive at question #7 of this packet, pass out copies of Reproducible #3 Cost- Effective Ways to Save Water at Home. This handout will help them think about the personal steps they would be willing to take to save water. 3. Review the answers as a class. Then, hold a short discussion using the following questions: Was there anything on this sheet that sounded familiar or that you knew already? What did you learn that was new to you? What surprised you most? What new questions did this packet raise for you? What would you like to know more about? What information do you think is important to share with your family? Do any of these issues affect your community or region more than others? Activity Two: Linking Energy Use and Water 1. Pass out copies of Reproducible #4 Discovering the Connections between Energy Use and Water. This packet could be completed in class with students working in small groups, or as a homework assignment. 2. When finished, review the answers as a class. Then, hold a short discussion using the following questions: Was there anything on this sheet that sounded familiar or that you knew already? What did you learn that was new to you? What surprised you most? What new questions did this packet raise for you? What would you like to know more about? What information do you think is important to share with your family? Do any of these issues affect your community or region more than others? 23 Exploring the Energy-Water Nexus: A Stakeholder Dialogue for Identification of Critical Issues, National Renewable Energy Lab,

8 Activity Three: Conduct a Home Water Audit 1. Explain that you would like each student to conduct an audit of water usage at their home. An audit involves determining how much water is used and identifying steps that can be taken to save water. Performing audits can help families save money on their water and utility bills. Conducting an audit can also make your students more conscious of how their family uses water and how water can be saved. Remind students that by saving water they are also saving energy and reducing the carbon emissions that go into the atmosphere. 2. Reproducible #6 Information on Conducting a Household Water Audit and Reproducible #7 Personal Water Audit contain a range of information about conducting home water audits to collect a variety of household and/or personal usage data. Walk students through the steps of conducting the audit, letting them know which information they will be collecting for their assignment. a. If they will be auditing their household water utilities bill or reading the water meter in their home, they will likely have to ask for adult guidance to obtain a copy of the bill or locate the water meter. b. The Water Footprint Calculator (found under Your Footprint Calculator at is a great online tool that will allow your students to calculate their extended water footprints (equal to the water required to produce the goods and services they consume). You may also recommend that students use online audits such as: North Carolina Cooperative Extension Service Water Quality and Waste Management s Saving Water and Saving Energy ( the U.S. EPA s WaterSense Calculator ( or the Maryland Department of the Environment Water Supply Program s Residential Water Audit ( c. You may even ask students to do more than one type of water audit and compare the results, making hypotheses to account for any differences. 3. Pass out copies of the relevant reproducibles, enough for each student to take home. As an assignment, have students complete the data discussed, being ready to report their results in class. Wrap-Up: Results and Reflection 1. Begin by listing a range of student water usage totals as calculated in their audit assignment on the chalkboard or whiteboard. Guide students in determining the class average of daily water usage. 2. Lead a discussion of the students audit results, water use, and availability. Use the following questions and answers as a guide: a. Were you surprised by your daily personal water usage? Did you imagine that you used more or less water each day? How does your personal total differ from the class average?

9 b. How much of your total water was actually used and how much was wasted down the drain? c. How much more water do you use than what actually comes from the faucet? How is this water is used? Remind students that a large majority of water used in the U.S. is in agriculture and industry. For example, it takes thousands of gallons of water to raise a cow to make a pound of beef or a carton of milk, and nearly all of their food and drink required water to process. In addition, almost every product they use required water to make, transport, etc. d. What factors affect the totals calculated today? e. How would your audit look if you did it on a weekday vs. a weekend? Think about washing a car, doing laundry, running the dishwasher, etc. f. What about summer vs. winter? Think about filling a pool, watering a garden or yard, etc. g. How do you think your water usage compares to other people in the U.S.? Ex: Southwest is very dry, Northwest is very wet, urban vs. rural, poverty levels, etc. h. How do you think your water usage compares to people in other countries? Consider climate, cost, availability, access, etc. i. Conditions such as drought, pollution, rising population, and unequal distribution of natural resources threaten our water supply, even in the U.S. What might happen if we were faced with extreme water shortages? Cost would go up, our usage would have to go down, access would be less reliable, conservation practices would become more common, etc. 3. Remind your students that they have been learning about a little-understood, but very important, idea that water and energy use are interconnected and the behaviors of individuals can have a major impact on water and energy conservation. Share these facts: If one out of every 100 American homes were retrofitted with water-efficient fixtures, we could save about 100 million kwh of electricity per year. This would save 80,000 tons of greenhouse gas emissions, which is equivalent to removing nearly 15,000 cars from the road for one year! 24 If 1% of American homes replaced their older, inefficient toilets with WaterSense labeled models, the country would save more than 38 million kwh of electricity enough to supply more than 43,000 households electricity for one month. 25 A rain barrel can lower household water bills by about $35 a month in the summer. 26 Save hundreds of gallons of water each summer and year-round by using a rain barrel to collect water for watering your lawn, garden, and outdoor plants. Don t let water run unnecessarily when washing dishes, brushing teeth, showering or other tasks. Letting the faucet run for five minutes uses about as much energy as letting a 60-watt light bulb run for 14 hours! Benefits of Water Efficiency, WaterSense. U.S. Environmental Protection Agency, Benefits of Water Efficiency, WaterSense. U.S. Environmental Protection Agency, 26 Rain Barrel Survey Results, DC Urban Gardeners, 27 Benefits of Water Efficiency, WaterSense. U.S. Environmental Protection Agency,

10 Lower the temperature on your water heater to 120 F; for every 10ºF reduction in temperature, you can save from 3% 5% on your water heating costs. 28 You can also avoid using hot water unless it is necessary. Fix leaks! A leak of one drip per second can cost $1 per month. At 60 drips per minute, you waste 8.64 gallons per day, 259 gallons per month, and just over 3,153 gallons per year. Think about all of that good, clean water just going to waste! 29 Encourage students to share other ideas about conserving water and/or energy. 4. Pass out an index card or a half-sheet of paper to each student. Explain that you will be asking them to respond to a series of questions. You will give them a minute or two to write their response to each question, but they should work silently. Questions: What are the most important ideas that you learned from these activities that you want to remember? What did you learn that you think everybody should understand and why? What is one fact you plan to share with your friends and family? What actions do you plan to take in your home? What questions do these activities raise about your future? If you had a chance to speak to a government or elected official about what you learned, what would you want to tell them? 5. Allow students to share their thoughts by asking them to read their responses to each question. Try to have every student contribute at least one idea during the discussion of the four questions. As they speak, record their ideas on large paper. End by highlighting themes that came out. Later, post their ideas on the classroom wall for all to read. Remind students about actions they can take to conserve resources. Extension: Raising Public and Political Awareness 1. Revisit the question, If you had a chance to speak to a government or elected official about what you learned, what would you want to tell them? and student responses in the Wrap- Up activity. 2. Go over student answers and ideas. Discuss the pros and cons of various approaches and solutions. Have the class vote on their favorite(s) and/or choose one or more ideas that are the most practical. As a class, write letters to the applicable school, district, or government official explaining the issues and presenting ideas for solutions. You may also choose to start petitions or write letters to the editor of your school or community newspaper. Extension: Hot Showers Can We Save Energy and Water? Ways to Save on Your Water Heating Bill, Energy Savers Blog, U.S. Department of Energy, Ways to Save on Your Water Heating Bill, Energy Savers Blog, U.S. Department of Energy,

11 1. Ask students how many minutes they shower. Five minutes? Ten? Twenty or more? In this activity, they will calculate how much water they actually use when showering. 2. Pass out copies of Reproducible # 8 Tracking Shower Time and Water Use. Tell them that you want them to track how many showers they take in a week and to time how long their showers last. Give them the dates of the week you would like them to gather data and have them record those dates on their sheet. 3. Explain that showerheads vary tremendously in the amount of water they use per minute. To make their results accurate, each student needs to calculate the flow rate of their showerhead. Go through these steps as they are outlined on the handout. 4. Ask your students to complete this handout as homework and announce the day they should bring their results to class for a discussion. 5. Discussion questions: What did you learn? How many of you found your showerhead was a low-flow model, one that uses 2.5 gallons per minute or less? How many of you found your showerhead was a very high-flow model, one that uses 7 gallons per minute or more? In the class, what is the range of water used for showers each week? How many people were surprised by how much (or how little) water they used for showers? Given that most bathtubs are gallons, at what point does it become more economical (and ecological) to take a bath instead of a shower? 6. Remind students about the connection between water and energy. The energy embedded in hot water not only includes the energy used to treat and transport water, it also requires further energy to heat it. Heating hot water with electricity is especially costly for families. In addition, the water that goes down the drain needs to be treated at the sewage treatment plant, and this requires more energy. Ask students what three things people can do to save water and energy through showers? They can take shorter showers (or turn off the water while shampooing and shaving), they can take less steamy showers, and they can replace showerheads with more water-saving models. Would any students be willing to do one of all of these things? Why or why not? Extension: Reducing Hot Water Use in the Home 1. Explain to your students that you d like them to research some of the behaviors, new technologies and appliances that help to reduce the use of hot water. One of the specific ways students can save water and energy is to help reduce the amount of hot water used in their homes.

12 2. Divide your students into research groups. Assign each group a topic. Topics could include: Compare the flow rates of old showerheads to new low-flow models. Compare water usage in old washing machines to new energy-star models. Why it is important to fix faucet leaks and how much water (and energy) can be lost when they are not fixed? New faucet fixtures that save water (and energy!) Ways to make hot water heaters more efficient. List behaviors and actions that will have the most impact on reducing hot water usage at home. 3. The three sites listed below will provide a helpful start for your students. There are other useful items on the resource list for this lesson, but your students will certainly find more beneficial resources as they do their research Have students present their findings to the class through a presentation or poster session. CONCLUSION Students were introduced to the important links between our energy use and water use. They learned where energy is used throughout the water treatment, delivery, and waste treatment systems, and read an article about the large amount of water consumed in the process of producing electricity and burning fossil fuels. At home, students conducted a personal and/or household water audit to determine how much water they use and how they could cut back, saving both water and energy. Finally, students began to consider how the links between water and energy may affect their future. LESSON PLAN CREDITS Margaret Pennock Author Curricula Writer, Middle School Science Teacher, Sidwell Friends School David Wood Author Curricula Writer, 8 th Grade Science Teacher, Sidwell Friends School Brenna Holzhauer Author, Editor Education Manager, Mary Beall Researcher Education Intern,

13 Name: Date: Discovering the Connections between Water Use and Energy GETTING STARTED 1. List at least five things that your family uses tap water for in your home. Interesting Fact: In a study of 1,200 homes in 14 cities, the top use of household water was for flushing toilets (26.7% of water used) Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p Energy Requires Water, National Renewable Energy Laboratory, accessed February

14 2. According to Diagram One, how much water does a typical person use per day for direct household activities such as showers, laundry, cooking, and watering the lawn? Interesting Fact: One bath can use gallons of water; a typical shower uses 3-5 gallons per minute! 32 GETTING WATER TO YOUR HOME 3. Most people do not think about where their tap water comes from, much less the energy used to get it to your home. There are many steps involved in the process of getting tap water to your home, and once it goes down the drain it also needs to be treated. Using the table below, look at the list of steps in the process of delivering and treating tap water. For each step, decide if you think energy is required by putting a check in the correct column. You can look at Diagram Two (below) to help visualize some of these steps. Table 1: Steps in the Process of Getting Water to Your Home Step Description of Step # 1. Water is pumped from under the ground to a treatment plant where water is treated and disinfected. 2. In some regions, the source of drinking water is a lake or river. Water moves by gravity from its source to the treatment plant. 3. The treatment process includes the injection of substances such as chlorine, ammonia and lime to kill germs and balance the ph of the water; the rapid mixing of water; the removal of impurities that have settled to the bottom of tanks; the filtering of water to remove fine particles; and sometimes the use of UV lights to kill remaining bacteria. 4. Once treated, the water is pumped to storage tanks or to reservoirs. 5. Water is often pumped from storage tanks and reservoirs to homes and businesses for use. 6. In the home, people heat water for showers, laundry, and cooking. People also cool water to make cold drinking water or ice. Some homes use additional purifiers or pump Check if energy is required Check if energy is not required 32 Saving Water and Saving Energy, Waste Quality and Water Management, North Carolina Cooperative Extension Service,

15 their water to distant places on their property, say to feed farm animals. 7. Once water is flushed down a toilet or washed down a drain, it travels to a wastewater treatment plant through underground pipes. 8. People with septic systems don t have their wastewater transported to wastewater treatment facilities through pipes. Instead, trucks pump out the waste that is stored in an underground tank, and the waste is transported by truck to a proper wastewater treatment center. 9. Water is pumped through various steps of the wastewater treatment process to remove solids and excess nutrients as well as to kill germs. 33 Take a moment to think about the major steps in getting water to your home: Transporting water from its source to the water treatment plant. Treating the water to make it drinkable. Transporting the water to storage tanks or reservoirs before transporting it to your home. Transporting used water to the wastewater treatment plant. Treating the used water before returning it to a stream, river, or other body of water. 33

16 Remember, each of these steps requires the use of energy. In some cases, this energy comes from the heat produced by the direct burning of oil or gas. In some steps, electricity is required, most of which comes from oil, gas, coal, and nuclear power. Interesting Fact: 3-4% of all of the electricity used in the U.S. is used to treat and transport drinking water and wastewater. Even if all of this power came from a relatively cleaner source such as natural gas, the energy required would release carbon dioxide equivalent to more than 4 million cars In Table One, think about the one step that did not require the use of energy. An example of this is in Washington, D.C., which gets its drinking water from the Potomac River. The source of the water is about ten miles from the water treatment plant, where there is a large topographic drop in the river and a large waterfall. (The water then travels through pipes to the treatment center.) Why do you think this location was selected over a spot on the river very close to the treatment plant? Interesting Fact: Aqueducts carry water from its source to treatment plants and vary considerably in length. The one in Washington, D.C. is less than 10 miles long. The length of the Colorado aqueduct is 242 miles! This aqueduct carries water from Colorado to southern California. 35 SAVING ENERGY IN THE WATER PROCESS 5. Whenever possible, cities and towns place their wastewater treatment plants (those that clean used water) in areas of lowest elevation. Why do you think this is done? Interesting fact: Most of the energy used in a municipal water system is used to pump water. For a city of 50,000 people, approximately 80% of the energy used in the 34 Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p

17 municipal water system is dedicated to pumping water. 36 The rest is used for treatment plant operations. You can see why using gravity is important, if it can be utilized. 6. a) In question three, five steps were identified in the process of transporting and treating water. Which two of these steps are the most important to human health? b) Interesting question: While treatment plants may be able to increase the efficiency of their equipment, would you want them to skimp on the process of treating water in order to save money? 7. Look again at Table One. What steps can you and your family take to save water and thus energy? Interesting fact: Families can install a variety of cost-effective technologies to reduce the use of water and energy and to save money. In California, it is estimated that families could reduce their water use by 35% by using these technologies. 37 WRAP-UP 8. True or False? Please read the following statements and decide whether they are true or false and why. a) Reducing the amount of water I use saves energy. Explain: 36 Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p. 19.

18 b) Reducing the amount of hot water I use saves my family money. Explain: c) Reducing the amount of water I use reduces emissions that contribute to global climate change. Explain: d) The population of the U.S. is expected to rise significantly in the next 100 years, possibly doubling. 38 It s important for our future to conserve water. (See Diagram Three below). Explain: 38

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20 Discovering the Connections between Water Use and Energy ANSWER KEY GETTING STARTED 1. List at least five things that your family uses tap water for in your home. drinking, cooking, laundry, showers/bath, flushing toilets, watering the lawn Interesting Fact: In a study of 1,200 homes in 14 cities, the top use of household water was for flushing toilets (26.7% of water used) According to Diagram One, how much water does a typical person use per day for direct household activities such as showers, laundry, cooking, and watering the lawn? 100 gallons Interesting Fact: one bath can use gallons of water; a typical shower uses 3-5 gallons per minute! Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p Energy Requires Water, National Renewable Energy Laboratory, accessed February

21 GETTING WATER TO YOUR HOME 3. Most people do not think about where their tap water comes from, much less the energy used to get it to your home. There are many steps involved in the process of getting tap water to your home, and once it goes down the drain it also needs to be treated. Using the table below, look at the list of steps in the process of delivering and treating tap water. For each step, decide if you think energy is required by putting a check in the correct column. You can look at Diagram Two (below) to help visualize some of these steps. Table 1: Steps in the Process of Getting Water to Your Home Step Description of Step # 1. Water is pumped from under the ground to a treatment plant where water is treated and disinfected. 2. In some regions, the source of drinking water is a lake or river. Water moves by gravity from its source to the treatment plant. 3. The treatment process includes the injection of substances such as chlorine, ammonia and lime to kill germs and balance the ph of the water; the rapid mixing of water; the removal of impurities that have settled to the bottom of tanks; the filtering of water to remove fine particles; and sometimes the use of UV lights to kill remaining bacteria. 4. Once treated, the water is pumped to storage tanks or to reservoirs. 5. Water is often pumped from storage tanks and reservoirs to homes and businesses for use. 6. In the home, people heat water for showers, laundry, and cooking. People also cool water to make cold drinking water or ice. Some homes use additional purifiers or pump their water to distant places on their property, say to feed farm animals. 7. Once water is flushed down a toilet or washed down a drain, it travels to a wastewater treatment plant through underground pipes. 8. People with septic systems don t have their wastewater transported to wastewater treatment facilities through pipes. Instead, trucks pump out the waste that is stored in an underground tank, and the waste is transported by truck to a proper wastewater treatment center. Check if energy is required Check if energy is not required 42 Saving Water and Saving Energy, Waste Quality and Water Management, North Carolina Cooperative Extension Service,

22 9. Water is pumped through various steps of the wastewater treatment process to remove solids and excess nutrients as well as to kill germs. 43 Take a moment to think about the major steps in getting water to your home: Transporting water from its source to the water treatment plant. Treating the water to make it drinkable. Transporting the water to storage tanks or reservoirs before transporting it to your home. Transporting used water to the wastewater treatment plant. Treating the used water before returning it to a stream, river, or other body of water. Remember, each of these steps requires the use of energy. In some cases, this energy comes from the direct burning of oil or gas. In some steps, electricity is required, most of which comes from oil, gas, coal, and nuclear power. Interesting Fact: 3-4% of all of the electricity used in the U.S. is used to treat and transport drinking water and wastewater. Even if all of this power came from a relatively cleaner source such as natural gas, the energy required would release carbon dioxide equivalent to more than 4 million cars Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p. 1-2.

23 4. In Table One, think about the one step that did not require the use of energy. An example of this is in Washington, D.C., which gets its drinking water from the Potomac River. The source of the water is about ten miles from the water treatment plant, where there is a large topographic drop in the river and a large waterfall. (The water then travels through pipes to the treatment center.) Why do you think this location was selected over a spot on the river very close to the treatment plant? Gravity is used to transport the river water to the treatment plant. This is possible because of the large topographic drop in the river. Without gravity, energy would have to be used to pump the water. Thus, using gravity saves energy and money. Interesting Fact: Aqueducts carry water from its source to treatment plants and vary considerably in length. The one in Washington, D.C. is less than 10 miles long. The length of the Colorado aqueduct is 242 miles! This aqueduct carries water from Colorado to southern California. 45 SAVING ENERGY IN THE WATER PROCESS 5. Whenever possible, cities and towns place their wastewater treatment plants (those that clean used water) in areas of lowest elevation. Why do you think this is done? Less energy is required to pump used water from homes and businesses to the wastewater treatment plant. Using gravity to help in the transportation process saves energy and money. Interesting fact: Most of the energy used in a municipal water system is used to pump water. For a city of 50,000 people, approximately 80% of the energy used in a municipal water system is dedicated to pumping water. 46 The rest is used for treatment plant operations. You can see why using gravity is important, if it can be utilized. 6. In question three, five steps were identified in the process of transporting and treating water. Which two of these steps are the most important to human health? Treating drinking water and treating wastewater. If these are not done properly, people can get sick from bacteria or unsafe chemicals in the water. Interesting question: While treatment plants may be able to increase the efficiency of their equipment, would you want them to skimp on the process of treating water in order to save money? It s very important that treatment plants do their job correctly. Skimping on the treatment process in order to save energy and money would put human and environmental health at risk, and would break several regulations such as the Clean Drinking Water Act. 7. Look again at Table One. What steps can you and your family take to save water and thus energy? Answers will vary but involve reducing the total amount of water used and the amount of water that needs to be heated or cooled Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p. 17.

24 Interesting fact: Families can install a variety of cost-effective technologies to reduce the use of water and energy and to save money. In California, it is estimated that families could reduce their water use by 35% by using these technologies. 47 WRAP-UP 8. True or False? Please read the following statements and decide whether they are true or false and why. a) Reducing the amount of water I use saves energy. Explain: True. Less energy is used to transport and treat the water before and after use. b) Reducing the amount of hot water I use saves my family money. Explain: True. Heating water uses energy. Reducing the amount of hot water used will reduce the cost of utility bills. c) Reducing the amount of water I use reduces emissions that contribute to global climate change. Explain: True. Energy is used to provide water as well as to heat and cool water. When oil and gas are used to heat water, carbon dioxide is released into the atmosphere. A considerable amount of our electricity is produced by burning coal. This electricity may be used to treat, transport, and heat/cool your water. The burning of coal releases carbon dioxide into the atmosphere, contributing to global climate change. d) The population of the U.S. is expected to rise significantly in the next 100 years, possibly doubling. 48 It s important for our future to conserve water. See Diagram Three. Explain: True. More people mean a bigger demand for water, and thus a larger demand for energy, and therefore more emissions that contribute to global climate change. Many of the areas with the greatest population growth are also the areas that are already experiencing water shortages. 47 Cohen, R., Nelson, B, and Wolff, G. (2004. Energy Down the Drain: The Hidden Costs of California s Water Supply. NRDC and the Pacific Institute. p

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26 Cost-Effective Ways to Save Water at Home Adapted from the U.S. Environmental Protection Agency s WaterSense Simple Steps 50 Inside: The average household spends as much as $500 per year on its water and sewer bill but could save about $170 per year by retrofitting with water-efficient fixtures and incorporating water-saving practices. Check your toilet for leaks by adding food coloring to the tank. If it is leaking, color will appear in the bowl within 15 minutes. (Note: food coloring can stain your tank if it sits for too long). Installing a low-flow toilet can save your family more than $90 annually and $2,000 over the lifetime of the toilet. Installing a faucet aerator or low-flow faucet can increase the efficiency by 30%. Repair leaky faucets or showerheads. One drip per second can waste more than 3,000 gallons per year. Filling a bathtub requires up to 70 gallons. A 5-minute shower uses gallons. Turning off the tap while you brush your teeth can save 8 gallons per day! Wash only full loads of dishes or clothes or lower the water settings for smaller loads. Replace your old washing machine with a high-efficiency model to use up to 50% less water and electricity. Outdoors: The average suburban home uses at least 30% of its water for outdoor purposes (up to 70% in dry climates!) More than 50% of landscape water is wasted due to evaporation, wind, or overwatering. Water your lawn or garden during cooler morning hours to reduce evaporation. Use sprinklers that produce droplets instead of mist or use soaker hoses and trickle irrigation. Be sure you are not watering the street or sidewalk! Learn the water needs of your plants and landscaping. Too much fertilizer increases your lawn s need for water. Raise your lawn mower blade to at least 3 inches. Taller grass promotes deeper roots and provides more shade, allowing better moisture retention. Plant native species appropriate to your climate. Use mulch around trees and plants to reduce evaporation and control weeds. The amount of money you save depends on the cost of water where you live, but using less water lowers your utility bill, along with preserving this limited resource for generations to come 50