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Fact Sheet - Water Pollution

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  • Drinking water derived from most public and some private wells is treated before it enters our homes. While some treatment is usually necessary, the costs of treatment and risks to public health can be reduced by ensuring that source water is protected from contamination.
  • Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production and mining activities, are a threat to source water.
  • Microbial contaminants are a threat to source water. Examples include viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.
  • Protection of drinking water sources reduces the treatment challenge for public water suppliers.
  • The United States has one of the safest water supplies in the world. Although drinking water often picks up low levels of some contaminants as it flows in rivers and collects in aquifers, these materials usually are not detected at harmful levels.
  • Episodes of serious drinking water contamination in the U.S. are infrequent and usually of short duration. However, treatment problems or extreme weather events may allow contaminants to enter water supplies.
  • If water contamination poses an immediate health threat, water suppliers are required by law to notify customers right away. Any violation of a drinking water standard requires public notice.
  • Children may be more susceptible to chemical contaminants that affect learning, motor skills, and sex hormones during important stages of growth.
  • Wells should be tested annually for nitrate and coliform bacteria to detect contamination problems early.
  • Fecal coliform and E. coli are bacteria whose presence indicates that water may be contaminated with human or animal wastes. Microbes in these wastes can cause short-term effects such as diarrhea, cramps, nausea, headaches, or other symptoms.
  • Certain minerals are radioactive and may emit forms of radiation known as photons and beta radiation (beta/photon emitters). Some people who drink water containing beta and photon emitters in excess of EPA's standard over many years may have an increased risk of getting cancer.


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