Wednesday, 3 April 2013


Community Water Treatment

Drinking water supplies in the United States are among the safest in the world. However, even in the U.S., drinking water sources can become contaminated, causing sickness and disease from waterborne germs, such as Cryptosporidium, E. coli, Hepatitis A, Giardia intestinalis, and other pathogens.

Drinking water sources are subject to contamination and require appropriate treatment to remove disease-causing agents. Public drinking water systems use various methods of water treatment to provide safe drinking water for their communities. Today, the most common steps in water treatment used by community water systems (mainly surface water treatment) include:

Coagulation and Flocculation
Coagulation and flocculation are often the first steps in water treatment. Chemicals with a positive charge are added to the water. The positive charge of these chemicals neutralizes the negative charge of dirt and other dissolved particles in the water. When this occurs, the particles bind with the chemicals and form larger particles, called floc.

Sedimentation
During sedimentation, floc settles to the bottom of the water supply, due to its weight. This settling process is called sedimentation.

Filtration
Once the floc has settled to the bottom of the water supply, the clear water on top will pass through filters of varying compositions (sand, gravel, and charcoal) and pore sizes, in order to remove dissolved particles, such as dust, parasites, bacteria, viruses, and chemicals.

Disinfection
After the water has been filtered, a disinfectant (for example, chlorine, chloramine) may be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the water from germs when it is piped to homes and businesses.
Learn more about water disinfection with chloramine and chlorine on the Disinfection page.
http://www.cdc.gov/healthywater/drinking/public/water_disinfection.html

Water may be treated differently in different communities depending on the quality of the water that enters the treatment plant. Typically, surface water requires more treatment and filtration than ground water because lakes, rivers, and streams contain more sediment and pollutants and are more likely to be contaminated than ground water.

Some water supplies may also contain disinfections by-products, inorganic chemicals, organic chemicals, and radionuclides. Specialized methods for controlling formation or removing them can also be part of water treatment. To learn more about the different treatments for drinking water, see the National Drinking Water Clearinghouse's Fact Sheet Series on Drinking Water Treatments
http://www.nesc.wvu.edu/techbrief.cfm

To learn more about the steps that are taken to make our water safe to drink, visit the United States Environmental Protection Agency's (EPA) Public Drinking Water Systems webpage.
http://www.epa.gov/safewater/pws/index.html

To learn more about the 90+ contaminants EPA regulates and why, visit EPA's Drinking Water Contaminants.
http://www.epa.gov/safewater/hfacts.html

Water Fluoridation

Community water fluoridation prevents tooth decay safely and effectively. Water fluoridation has been named one of 10 great public health achievements of the 20th century. For more information on the fluoridation process and to find details on your water system's fluoridation, visit CDC's Community Water Fluoridation page.
http://www.cdc.gov/fluoridation/

Consumer Confidence Reports

Every community water supplier must provide an annual report, sometimes called a Consumer Confidence Report, or "CCR," to its customers. The report provides information on your local drinking water quality, including the water's source, contaminants found in the water, and how consumers can get involved in protecting drinking water.

View the CDC's guide to Understanding Consumer Confidence Reports
http://www.cdc.gov/healthywater/drinking/public/understanding_ccr.html

See if your CCR is posted online (United States Environmental Protection Agency Local Drinking Water Information)
http://www.epa.gov/safewater/dwinfo.htm

Source:
http://www.cdc.gov/healthywater/drinking/public/water_treatment.html
Community Water Treatment

Drinking water supplies in the United States are amon...

No comments:

Post a comment