Drinking Water

Water covers nearly 75% of Earth's surface. Yet 97% of it is salty ocean water that cannot be used. Of the remaining freshwater (3%), most of it is frozen in glaciers and ice sheets and is not readily available to use. This means the remaining water, a little less than 1%, is all of the freshwater that is available on this planet for all the Earth's animals, plants and 6.6 billion people to share!

It is estimated that each person in the United States uses about 150 gallons of water each day. Most of this water is used for cooking, bathing, flushing toilets, laundry and landscaping. Surprisingly, out of those same 150 gallons of water, only about half a gallon is used for drinking. However, the standards and regulations that go into making water safe to drink in the United States make that half gallon of water extremely vital in terms of protecting everyone's health.

Safe Drinking Water Act

In 1974, Congress passed the Safe Drinking Water Act to ensure safe drinking water throughout the United States. The Act authorized the Environmental Protection Agency to set national drinking water standards for the maximum safe levels of numerous chemicals, metals and bacteria. National drinking water standards were also set for odor, color and turbidity (how clear the water looks). In addition, major requirements of the Safe Drinking Water Act include that all public water systems must provide water treatment, monitor drinking water quality and notify people about water system contamination.

Drinking water comes from surface and groundwater, either of which may contain harmful components of chemicals, bacteria or organisms that can cause disease. Because of possible threat of disease, water must go through an extensive treatment process before it is considered safe to drink. Drinking water treatment processes include:

• Flocculation: a chemical, such as alum or ferric chloride, is added to the water. This causes dirt and other small particles to join together into "floc" or large clumps.
• Sedimentation: Gravity is used to pull floc down to the bottom of a settling basin.
• Filtration: Small particles are separated from the water by using a porous barrier that traps the particles while allowing the water to pass through.
• Disinfection: Chlorine and other chemical disinfectants are added to the water to kill any remaining microorganisms that could be potentially harmful.

Nationally, government agencies such as the Environmental Protection Agency and the U.S. Geological Survey as well as professional associations such as the American Water Works Associations and the American Water Resources Association are active in a variety of drinking water issues. Locally in Southern California, the Metropolitan Water District and its member agencies such as West Basin Municipal Water District are also actively involved in ensuring that the drinking water that millions of people rely upon is of the highest quality.