- Who is responsible for reducing water pollution?
- Explain what a dead zone is and where you might find one?
- What is the leading cause of death for children around the world?
Vocabulary
dead zone A region hundreds of kilometers wide without fish or plant life due to lack of
oxygen in the water.
thermal pollution Water pollution created by added heat to water.
Points to Consider
- Water pollution not only harms human health and the environment. Consider how
this reduces the amount of water available to humans. - Fifty percent of all infectious diseases are caused by water pollution. What can be
done to reduce the number of pathogens that reach our freshwater supplies? - Ocean pollution harms some of the most productive sources of marine life. How can
we change our behaviors to protect marine life?
21.4 Protecting the Water Supply
Learning Objectives
- Describe several ways water can be conserved.
- Discuss how water is treated to eliminate harmful particles.
- State what governments and international organizations can do to reduce water pollu-
tion.
Water Treatment
The goal of water treatment is to make water suitable for such uses as drinking water,
medicine, agriculture and industrial processes.
People living in developed countries suffer from few waterborne diseases and illness, because
they have extensive water treatment systems to collect, treat, and redeliver clean water to
their people. Many undeveloped nations have few or no water treatment facilities.
Water treatment is any process used to remove unwanted contaminants from water (Figure
21.22). Water treatment processes are designed to reduce harmful substances such as sus-
pended solids, oxygen-demanding materials, dissolved inorganic compounds, and harmful