Why is water important? For what purposes you we need water? Do you need water to survive? Does your food need water to grow? What would the world do without water? These are all questions we ask when learning about how important water is.

If you are thirsty and need a glass of water, do you want a glass of dirty water or clean water to drink? Probably clean — or fresh — water is what you would rather have. Finding fresh water, however, is becoming more and more difficult as the population in the world grows. With more people around, the demand for fresh drinking water is increasing while the amount of fresh and clean water is becoming more and more scarce. Where do we get our drinking water? We turn on our faucets at home, but how do we know where that water originates? Did it come from the river running through the field behind your backyard, was it pumped out of the ground somewhere, or is it water from the ocean that has had the salt taken out of it? Well, it can be from many of these sources. Environmental engineers are responsible for making sure we have clean drinking water. These engineers learn about the properties of water, the different sources of water and how to clean up dirty water. Environmental engineers develop water treatment systems that clean up water from natural sources, like streams and snow pack, and they even develop systems that clean up water we have used and flushed down our toilets and drains. Of course, once water has been used, it is dirtied; and it can never be completely cleaned again.

About 75% of the Earth is covered in water. Where is the Earth's water located? Well, water on the Earth can be found in ocean, rivers, lakes, atmosphere, and even more water can be found underground, in areas called aquifers. The oceans are the largest water source, containing 97% of the Earth's water. Unfortunately, we cannot normally use this water for drinking because it is too salty. Engineers are working on ways to get the salt out of ocean water and make it usable for drinking, but these methods are very expensive and not used very often. Very little of the Earth's water is suitable to be used for drinking water. In fact, less than one percent of our water is in rivers, lakes and groundwater. We get most of our drinking water from these types of surface waters. Another way to get drinking water is from the atmosphere, such as rain and snow. What happens if you count on snow for water and it gets too weather becomes too warm? Well, snowmelt in the spring and summer actually provides a great source of fresh water for a lot of communities. It is estimated that 75% of water used in the western United States is from stored- up snowmelt.

We use a lot of water! Think of all the ways that you use water during the day. You most likely use water to drink, brush your teeth, take a shower or bath, cook, flush the toilet and wash your dishes. These are just a few ways we use water. Now think about this: do you leave the water running while you brush your teeth or hands? Well, most of us waste a lot of water somehow. The average person in the United States uses 125 gallons of water per day! We are using up our water fast. Engineers are working on ways to help us save some of this valuable fresh water. They have developed low-flush toilets and showers that use less water. Can you think of some things that you can do to ensure that there is water for the people/animals/plants of tomorrow?

Who can name a major source of water? Our water comes from oceans, rivers, lakes, the atmosphere and groundwater/aquifers. Which water body has the greatest amount of water? (Answer: The oceans contain 97% of the Earth's water.) Where do we get most of our drinking water? (Answer: We get most of our drinking water from surface water.) Why is ocean/sea water not used for us to drink? (Answer: It is too salty.) What are some things you think we should do to ensure that there is water for the people/animals/plants of tomorrow? (Answer: We can conserve water by being cautious about how much we use daily: turn off faucets, take shorter showers, water lawns less and when the weather is cooler [can help prevent loss due to evaporation], etc.) How do engineers help us get clean drinking water? (Answer: Environmental engineers design water treatment and wastewater treatment plants to clean and help conserve water for daily use.)

Environmental engineers are the ones who design water and wastewater treatment plants so that we can have clean water. Have students draw a picture of the water cycle using their source of drinking water and major water bodies in their state of which they are aware. They should be able to show with words and pictures how these water bodies contribute to the water cycle and how they do or do not provide water for their house/school, etc. Students can also integrate a water treatment plant if desired. This shows them that water has to go through a water treatment plant before it comes out of the tap in their home or school.

Using the same idea, students can also integrate a wastewater treatment plant showing that the water coming out of their house must be cleaned.