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Download a zip file that includes all the web pages and downloadable files from the student materialsFor the Instructor
These student materials complement the Water Science and Society Instructor Materials. If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty (and this box). Or you can download these pages in several formats that you can include in your course website or local Learning Managment System. Learn more about using, modifying, and sharing InTeGrate teaching materials.Global Freshwater Resources
Water use and treatment
Once taken for human use, water generally follows a path described by Figure 3 below. After undergoing treatment and distribution, it is used. In the broadest sense, water is constantly being re-used. Water that is taken from rivers or streams for domestic, industrial, or agricultural use was most likely also used by communities or farms up-stream, and subsequently treated and discharged. Over even longer timescales, the water in streams, lakes, and groundwater is the same water that has ever been on Earth – and those same molecules have undoubtedly cycled through many plants and animals before we were even around!
Depending on the nature of water use, it may be re-captured after treatment ("recycled water") for re-use. As we will see later in the semester, this re-use of water resources is one strategy to cope with water scarcity. The recycled water, depending on its quality, can be used for irrigation (i.e. for parks or golf courses), or for domestic supply. Once the water leaves the "use" loop, it is treated and discharged, typically into surface water bodies. In some cases, the treated water may be used to recharge aquifers instead, either through induced recharge systems, or at a smaller scale via passive filtration through soils – for example in leachfields. The discharged water, after mixing with water in the river, stream (or aquifer), becomes a water source for downstream or down-gradient users.
Source: California Energy Commision, California's Water - Energy Relationship, Final Staff Report, Nov 2005
Activate Your Learning
1. Do you know the source of domestic or municipal water in your hometown? If yes, what and where is it? If no, does it surprise you to realize that you don't know where your drinking water comes from?
2. Do you suppose that any of that water is used and then treated by others before being taken for your use?
3. Take a look at figure 3 above. Had you thought about your water as a substance that has a "life cycle" and is constantly being used, treated, released, and re-used? If not, does the idea make you uncomfortable?
