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 pollution.

Vocabulary

sewage treatment
water purification

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 (Figure below). Many underdeveloped nations have few or no water treatment facilities.

A wastewater treatment facility uses settling containers, filters, chemicals, and biological agents to remove impurities.

Wastewater contains hundreds of contaminants such as suspended solids, oxygen-demanding materials, dissolved inorganic compounds, and harmful bacteria. In a wastewater treatment plant, multiple processes must be used to produce usable water:

Sewage treatment removes contaminants, such as solids and particles, from sewage.
Water purification produces drinking water by removing bacteria, algae, viruses, fungi, unpleasant elements such as iron and sulfur, and man-made chemical pollutants.

The treatment method used depends on the kind of wastewater being treated and the desired end result. Wastewater is treated using a series of steps, each of which produces water with fewer contaminants.

KQED: Wastewater Woes: Sewage Spill in SF Bay

Large numbers of sewage spills into San Francisco Bay are forcing cities, water agencies and the public to take a closer look at wastewater and its impacts on the health of the bay. QUEST investigates the causes of the spills and what’s being done to prevent them. Learn more at: http://science.kqed.org/quest/video/wastewater-woes-sewage-spills-in-sf-bay/.

Reducing Water Pollution

Water pollution can be reduced in two ways:

Keep the water from becoming polluted.
Clean water that is already polluted.

Keeping water from becoming polluted often requires laws to be sure that people and companies behave responsibly. In the United States, the Clean Water Act gives the Environmental Protection Agency (EPA) the authority to sets standards for water quality for industry, agriculture, and domestic uses. The law gives the EPA the authority to reduce the discharge of pollution into waterways, finance wastewater treatment plants, and manage runoff. Since its passage in 1972, more wastewater treatment plants have been constructed and the release of industrial waste into the water supply is better controlled.

The United Nations and other international groups are working to improve global water quality standards by providing the technology for treating water. These organizations also educate people in how to protect and improve the quality of the water they use (Figure below).

Scientists control water pollution by sampling the water and studying the pollutants that are in the water.

What can individuals do to protect water quality?

Find approved recycling or disposal facilities for motor oil and household chemicals.
Use lawn, garden, and farm chemicals sparingly and wisely.
Repair automobile or boat engine leaks immediately.
Keep litter, pet waste, leaves, and grass clippings out of street gutters and storm drains.

Controlling Ocean Pollution

Because so much of the pollution that ends up in the oceans starts out on land, one way to reduce ocean pollution is to reduce pollutants in rivers and other effluent that ends up in the sea. Although it is extremely difficult to do because the ocean is so vast, pollution that is put directly into the ocean can be better regulated and monitored (Figure below).

Marine pollution can be controlled by regulation, such as preventing pumping of ballast water from ships.

Government and international agencies can pass laws, provide funding, and enforce laws to prevent and clean up ocean pollution. Several national and international agencies monitor and control ocean pollution, including the National Oceanic and Atmospheric Administration (NOAA) and the EPA.

The long-term effects of oil spills are not well understood. Although the waters contaminated by the Exxon Valdez spill have been free of contaminants for years, the rocks and sand beneath the surface on many beaches are still coated with oil. The best way to avoid these problems is to keep oil spills from happening. This requires better monitoring of the companies that are permitted to engage in drilling for oil and transporting oil. The recent spill into the Gulf of Mexico suggests that this type of monitoring is so far insufficient.

Conserving Water

Low-flow showerheads reduce the amount water used during showers.

As human population growth continues, water conservation will become increasingly important globally (Figure above), especially in developed countries where people use an enormous amount of water. What are some of the ways you can conserve water in and around your home?

Avoid polluting water so that less is needed.
Convert to more efficient irrigation methods on farms and in gardens.
Reduce household demand by installing water saving devices such as low-flow shower heads and toilets.
Reduce personal demand by turning off the tap when water is not being used and taking shorter showers.
Engage in water saving practices: water lawns less, sweep rather than hose down sidewalks, and others.

At Earth Summit 2002 many governments approved a Plan of Action to address the scarcity of water and safe drinking water in developing countries. One goal of this plan is to cut in half the number of people without access to safe drinking water by 2015. This is a very important goal and one made more difficult as population continues to grow.

Lesson Summary

Many technologies are available to conserve water as well as to prevent and treat water pollution.
Many underdeveloped countries cannot afford the technology to provide their citizens with clean water.
The best way to have clean water is to keep water from being polluted.
Conserving water is necessary to be sure that water will be available for as many uses as possible.

Review Questions

1. What is the purpose of water treatment and purification?

2. How can governments and international organizations help to reduce water pollution?

3. How can ocean pollution be controlled?

4. Name three things that a person could do to reduce pollution.

5. Name three ways that you could reduce your personal water use.

Points to Consider

Who is responsible for controlling water pollution?
What can governments and international organizations do to control pollution?
It is usually cheaper to dump polluted water without spending money to treat and purify the water. What incentives would convince industry to control water pollution?

Human Actions and Earth’s Waters