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Well FAQ

Frequently Asked Questions

Where does the drinking water in my home come from?
The drinking water that is supplied to our homes comes from either surface water or ground water. Surface water is collected on the ground, in a stream, river, lake, reservoir, or ocean. Ground water is obtained by drilling wells and is located below the ground surface in pores and spaces within rocks.

Public water systems usually provide treated water from surface and ground water for public use. Water treatment systems are either government or privately-held facilities that withdraw water from the source, treat it, and deliver it to our homes. For more information on public water systems, visit CDC's Healthy Water Public Water Systems page.

A private well uses ground water as its water source. Owners of private wells and other individual water systems are responsible for ensuring that their water is safe from contaminants. For more information on private wells and individual water systems, visit CDC's Healthy Water Private Wells page.
What are the main types of ground water wells?
According to the United States Environmental Protection Agency (EPA), there are three basic types of private drinking wells:
Proper well construction and continued maintenance are keys to the safety of your water supply. It is important to know the type of well you have. You may be able to determine the type of well you have by looking at the outer casing and cover of the well.
As a private well owner, should I have my well tested?
Yes, as a private well owner, you are responsible for ensuring that you well water is safe to drink. The United States Environmental Protection Agency (EPA) is responsible for making sure that the public water supply within the United States is safe. However, the EPA does not monitor or treat private well drinking water. For information on testing your well water, visit Healthy Water's Well Testing.
How do contaminants (germs and chemicals) get into my well water?
A private well uses ground water as its water source. There are many sources of contamination of ground water. Here is a list of the most common sources of contaminants:
  • Naturally occurring chemicals and minerals (for example, arsenic, radon, uranium)
  • Local land use practices (fertilizers, pesticides, livestock, animal feeding operations, biosolids application)
  • Manufacturing processes
  • Sewer overflows
  • Malfunctioning wastewater treatment systems (for example, nearby septic systems)
My well water has a funny smell or taste; should I worry about getting sick?
Any time you notice a significant change in your water quality, you should have it tested. A change in your water's taste, color, or smell is not necessarily a health concern. However, a change could be a sign of a serious contamination problem.
What germs and chemicals should I test for in my well?
Several water quality indicators (WQIs) and contaminants that should be tested for in your water are listed below. A WQI test is a test that measures the presence and amount of certain germs in water. In most cases, the presence of WQIs is not the cause of sickness; however, they are easy to test for and their presence may indicate the presence of sewage and other disease-causing germs from human and/or animal feces. For more information on these contaminants and WQIs, please see the Healthy Water Well Testing page.

Water Quality Indicators:

  • Total Coliforms
  • Fecal Coliforms / Escherichia coli (E. coli)
  • pH

  • Nitrate
  • Volatile Organic Compounds (VOCs)
Other germs or harmful chemicals that you should test for will depend on where your well is located on your property, which state you live in, and whether you live in an urban or rural area. These tests could include testing for lead, arsenic, mercury, radium, atrazine, and other pesticides. You should check with your local health or environmental department to find out if any of these contaminants are a problem in your region.

Please remember that if your test results say that there are germs or chemicals in your water, you should contact your local health or environmental department for help in interpreting the test, test your water more often, and receive guidance on how to respond to the contamination.
When should I have my well tested?
You should have your well tested once each year for total coliform bacteria, nitrates, total dissolved solids, and pH levels. If you suspect other contaminants, you should test for those as well. However, spend time identifying potential problems as these tests can be expensive. You should also have your well tested if:
  • There are known problems with well water in your area
  • You have experienced problems near your well (i.e., flooding, land disturbances, and nearby waste disposal sites)
  • You replace or repair any part of your well system.
  • You notice a change in water quality (i.e., taste, color, odor)
Who should test my well?
State and local health or environmental departments often test for nitrates, total coliforms, fecal coliforms, volatile organic compounds, and pH (see above). Health or environmental departments, or county governments should also have a list of the state-certified (licensed) laboratories in your area that test for a variety of Water Quality Indicators (WQIs) and contaminants.

For more information, visit one of the links below or contact your local health department or the EPA Safe Drinking Water Hotline at (800) 426-4791.

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    Atlanta, GA 30333
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Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
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