Contamination in drinking water sources or watersheds can negatively affect the organisms that come in contact with it. The affects can be severe — causing illness or, in some cases, even death. It is important for people to understand how they can contribute to the contaminants in drinking water and what treatment can be done to counter these harmful effects. Students will learn about the various methods developed by environmental engineers for treating drinking water in the United States.

Engineers design many chemical and filter systems to make water safe for drinking and bathing. Some of the most important services provided in a community are the water and sewage treatment plants designed by engineers. Engineers also design treatment processes for the unclean water from paper processing plants or other industrial factories. Water must be clean when it leaves the factory, or else it will contaminate soil, water and air even further. filter drinking water treatment tap water environmental engineer contaminants pollution sedimentation disinfection After this lesson, students should be able to: Identify several processes used to treat water to make it safe to drink. Use vocabulary to help explain drinking water treatment. Describe how engineers use technology to help solve an individual or community drinking water problem. Describe contributions to the advancement of drinking water treatment made by people in different times in history. Show the students a glass of muddy water. Can you hypothesize where it came from? Does anyone know what is in the water? Would you want to drink this if it came from your kitchen tap? Probably not. People have been trying to get water clean enough to drink for centuries. During the 1700s and 1800s, people developed early ways to filter water to make it clean. They also discovered that there were microscopic bacteria and diseases that can travel in water that can make us sick. Today, environmental engineers have the job of cleaning up water to make it drinkable for communities. Environmental engineers are concerned about making drinking water safe for people to drink. They design the treatment facilities for drinking water processes, and they are responsible for getting rid of the contaminants and bacteria in untreated water that may make people sick. There are several processes that they use, including: coagulation, in which a powdery chemical, called a coagulant, is added to the water); and flocculation, a mixing process that makes particles stick together into clumps called flocs. After the flocs begin to form, the water flows into a large basin so that the big clumps can settle to the bottom, where they are removed. Sedimentation is the settling process that removes most of the big particles from the water, but there may still be some small particles left in the water. To remove these remaining particles, the water flows through a filter. Lastly, engineers in the United States also disinfect the water. Disinfection is often performed by adding chlorine to the water to kill germs. After all these steps, it is now clean enough to drink! In addition to designing ways to treat water, environmental engineers are called on when water quality in a drinking water facility changes or the design/machinery is not cleaning the water properly. These engineers figure out how to fix the problem and clean up the contaminated water. Today, we are going to work to clean up this glass of muddy water enough to drink it. Water engineering is a large and diverse branch of civil and environmental engineering. In one way or another, civil engineers are involved in almost every part of the water cycle - from the time water falls as rain until it is returned to the sea. Water engineers design and help build dams to create water storage reservoirs, use hydropower to generate electricity, divert water through tunnels, canals and pipelines to provide irrigation, transport water to cities, and supply safe drinking water to homes and industries (http://www.ice.org.uk/education/homepage/civil_engineers_do.asp). People have been treating water to make it safe to drink for a long time. Originally, people thought water was safe to drink if it was clear, so they worked to remove cloudiness ( turbidity). Early Egyptian paintings show that ancient Egyptians filtered their water, and it is believed that they used alum, a chemical that is still used for water treatment today. During the 1700s and 1800s filtration was developed to even further clear the suspended particles and clear up the water. In 1855, John Snow proved cholera is a waterborne disease caused by sewage; and in the 1880s, Louis Pasteur further described the ability of microscopic bacteria to travel through water. Federal regulation of drinking water in the United States started in the early 1900s, but regulation did not become strict until the Safe Water Drinking Act of 1974. This law underwent changes in 1986 and 1996 and is now governed mostly by the United States Environmental Protection Agency (US EPA). (For more on the history of drinking water, see http://www.epa.gov/safewater/dwh/treat.html under the "History of Drinking Water Treatment" and .) Today, the EPA is responsible for creating standards in the United States for water that is supplied to people to drink. Some people that use their own water wells are using water not regulated by the EPA. Most states are responsible for making sure that water meets the drinking water standards set by the EPA, but some states have chosen to let the EPA keep that responsibility. The Federal and state agencies can take local water distributors to court for not meeting the EPA standards. The largest cities in the United States get their water from surface water - lakes, rivers and reservoirs. Water taken from any surface source usually has some amount of debris (i.e., sticks, leaves, dirt) in it. It can also contain small amounts of pathogens (substances that can cause disease). Untreated water, called "raw water" is sent to a drinking water treatment facility to make it safe to drink, or potable. At the drinking water treatment facility, the water flows through many different processes to remove any contaminants. The first step in treating surface water is a little bit strange: we add a powdery chemical, called a coagulant, to the water. Although it may seem strange to add powder to water to make it clean, coagulants actually work very well. Coagulants make the particles in the water stick together in clumps. The coagulant is mixed into the water very quickly so that it gets evenly spread around. Next, the water is gently stirred so that the particles bump into each other and stick together. When particles stick together, they grow into clumps called flocs, so this gentle mixing process is called flocculation. After the flocs begin to form, the water flows into a large basin so that the big clumps can settle to the bottom, where they are removed. This settling process, called sedimentation, removes most of the big particles from the water, but there may still be some small particles left in the water. To remove these remaining particles, the water flows through a filter. In most water treatment facilities, filters are made of a special kind of sand, and the filters actually look like big sandboxes. After flocculation, coagulation, sedimentation and filtration, most of the contaminants are removed from the water. However, since everyone needs to drink water, it is wise to be extra safe, so engineers in the United States disinfect the water. Disinfection is often performed by adding chlorine to the water to kill germs. Some water treatment facilities also use other processes to treat water, such as using carbon to remove chemicals in the water, or ultraviolet light for disinfection. Many communities get water from a well in the ground. Ground water-supplied systems bypass some of the steps listed above because the pores, or spaces, in the dirt act as a natural filter. Different treatment systems use slightly different processes because water from different sources might contain different kinds or amounts of contamination. Everyone has to drink water, so it makes sense to think about where drinking water comes from and how we can keep it safe. Citizens can get involved in protecting their water resources by voting on land usage proposed by the local government and agencies as well as inform their local water suppliers of changes in the water quality or suspected contamination in the community. Something that soils, stains, corrupts or infects by contact or association. A chemical that makes particles in water stick together. A gentle stirring process by which particles stick together and grow into flocs. A clump of particles in water created by flocculation. The process of allowing water to sit so that particles drop to the bottom of the container and are removed. To free from infection especially by destroying harmful microorganisms. To treat with chlorine for disinfection. Cloudiness of water. Water that has not been treated. Water that is safe for people to drink. Straining out the Dirt From Lake to Tap Discuss with the students issues related to conservation of water in our country and in developing countries. Can they think of why water conservation is an issue? Ask students if they can think of anything they could do to help keep our water resources clean. Encourage the students to conserve water and discuss why it is important. (Expected answer: Everyone has to drink water, so it makes sense for everyone to think about where drinking water comes from, and how we can keep it safe.) Discussion Questions: Ask the students and discuss as a class. Have you ever thought about the source for drinking water? Would you drink water out of the gutter next to the road? Why not? Would you want to drink muddy water? Can you think of any ways to make muddy water clean? Would your method work if you wanted to make a lot of muddy water clean (like a million gallons or more)? Voting: Ask a true/false question and have students vote by holding thumbs up for true and thumbs down for false. Count the votes and write the totals on the board. Give the right answer. True or False: Ancient Egyptians treated their water to make it safe to drink. (Answer: true) True or False: Bacteria in water often make people sick in the United States. (Answer: False; engineers have designed systems to treat the water that most people drink.) True or False: One way to remove particles from water is to let it sit for a long time. (Answer: True; the particles will settle at the bottom — which is how sedimentation works.) True or False: The first step in water treatment is to add powder to the water. (Answer: True; a powdery chemical, a coagulant, is added to help with flocculation.) True or False: Filtering and disinfection are not important steps in drinking water treatment. (Answer: False; filtering and disinfection get rid of the smallest particles and bacteria from our drinking water.) True or False: Environmental engineers have the job of cleaning up water to make it drinkable for communities. (Answer: true) True or False: Environmental engineers only work with new drinking water treatment facilities. (Answer: False; environmental engineers are called on when water quality in an existing drinking water facility changes or the design/machinery is not cleaning the water properly.) Vocabulary Mix-Up: Write either the term or the definition of the ten vocabulary words on slips of paper. Mix them up, and then divide the slips among the students. Ask each student to match his or her term with its definition (or vice versa). After students have found their partner, ask each pair to read their term and definition out loud. At the end, give a brief explanation of the concepts. Concept Reflections / Journal Writing: Have the students reflect on the drinking water pollution and write a journal entry on their thoughts. Roundtable: Have the class form into teams of 3-5 students each. Ask the class a question with several possible answers. Have the students on each team make a list of answers by taking turns writing down ideas on a piece of paper. Students pass the list around the group until all ideas are exhausted. Have teams read aloud the answers and write them on the board. Ask the students: How would you remove or minimize pollutants in drinking water? (Answer: The first step in treating surface water is to add a powdery chemical, called a coagulant, to the water. Coagulants make the particles in the water stick together in clumps. When particles stick together, they grow into clumps called flocs, so this gentle mixing process is called flocculation. After the flocs begin to form, the water flows into a large basin so that the big clumps can settle to the bottom, where they are removed. This settling process, called sedimentation, removes most of the big particles from the water. To remove any of the remaining smaller particles, the water flows through a filter, made of a special kind of sand. After flocculation, coagulation, sedimentation and filtration, most of the contaminants are removed from the water. However, since everyone needs to drink water, disinfection is often performed by adding chlorine to the water to kill any remaining germs.) Friction Boggle!: Repeat the same activity as above, except when the teams read aloud their answers and write them on the board, ask if any other teams came up with the same idea. If any other teams have the same answer on their sheet, they have to cross that answer out on their list. The team that ends up with the most "unique" ideas, wins. Take a tour of your local drinking water treatment facility, or ask someone who works there to visit your class to explain how it works. Internet search: How do people in other countries treat their water? What are some inexpensive ways to make water safe to drink (examples: http://www.sodis.ch/, http://www.potpaz.org/pfpfilters.htm) Cleaning water with dirt? Have students investigate an experiment using soil to learn how dirt can work as a filter: http://soils.gsfc.nasa.gov/filter/filter.htm. There are great water posters that can be ordered (free of charge) from the U. S. Geological Survey at: http://water.usgs.gov/outreach/OutReach.html. Have students order a variety of posters for their classroom or the school. The Institute of Civil Engineers, Education Zone, "What Do Civil Engineers Do?" http://www.ice.org.uk/education/homepage/civil_engineers_do.asp New Jersey American Water Works Association, Kids' Water Zone, "Water Treatment and Distribution to Your Home," http://www.njawwa.org/kidsweb/treatment/treatment_distrib_to_home.htm U.S. Environmental Protection Agency, Ground Water & Drinking Water, "How is drinking water treated?" http://www.epa.gov/safewater/dwh/treat.html U.S. Environmental Protection Agency, Ground Water & Drinking Water, "Drinking Water and Health: What you need to know," http://www.epa.gov/safewater/dwhealth.html U.S. Environmental Protection Agency, Ground Water & Drinking Water, "Drinking Water & Ground Water Kids' Stuff," http://www.epa.gov/OGWDW/kids/treat.html