Testing Recommendations for Private Drinking Water Wells

While many private water systems provide water that is safe and of good quality, it is not uncommon to have one or more water quality problems. Some such as iron or hydrogen sulfide are quite noticeable. Others, particularly those that are health concerns such as nitrate and pesticides, often require testing to detect.

Unlike public water systems, private well owners in most states are not required to regularly test their wells or correct water quality problems. It is each individual homeowner’s responsibility to decide what tests to perform and make determinations regarding the safety and quality of the home water supply based on the water test results.

Testing recommendations often vary from state to state, however, there are a few key tests that should be regularly performed on every private well water system. Additional testing may be recommended if your well meets certain criteria. Criteria for further testing is generally based on the following:

  1. Types of land-use or other potential sources of contamination near your well;
  2. Geologic materials that a well is drilled into;
  3. Components of your household plumbing system.

Check the U.S. Environmental Protection Agency – State Private Drinking Water Wells Web Sites page to locate information that is specific to your community. This site will link you to agencies with private well water education responsibilities in your state.

Here are some general guidelines of recommended tests to perform on a private water system.

Figure 1. Testing recommendations for private wells. (based on Wisconsin guidelines)
Contaminant Which wells or homes should be tested? How often should I test?
Coliform Bacteria Every well Test once every year, or when there is a change in taste, color or odor
All newly constructed wells or when you first move into a new home. Test initially, and once every 5-10 years if levels are less than 2 mg/L.
Wells within ¼ mile of an agricultural field or animal feed lot Test annually
Well used by pregnant women and infants Test before pregnancy and at time of birth.
Wells that have levels above 2 mg/L Test annually
Arsenic Every well Test once
Wells that have detected arsenic in previous tests. Test annually if arsenic is present or iron levels appear to be increasing.
Pesticides Wells within ¼ mile of agricultural fields or areas where pesticides are manufactured, stored or mixed. Test once every 5-10 years.
Lead Homes with copper plumbing installed before 1985 or containing brass components Consider one time test
Copper Homes with new copper plumbing. Test initially and retest after 6 months
Homes where water is used to prepare infant formula or homes where residents are experiencing repeated symptoms of nausea, diarrhea or abdominal cramps. Two tests, one first draw sample in the morning and one after flushing faucet for 2-3 minutes.
Radium Wells in specific geologic regions Consult your local health department
Uranium Every well Test once
Wells that have detected uranium in previous tests. Test annually if uranium is present or iron levels appear to be increasing.
Radon Homes with high indoor air radon that cannot be reduced by sealing basement cracks and ventilation Generally not necessary unless methods of reducing indoor air radon fails
Fluoride Wells used by infants and preschool-aged children Test when infant is born or if first moving into new home with a well
VOCs (solvents, gasoline or fuel oil) Wells within ¼ mile of a landfill, underground fuel or gasoline tank; or wells within ¼ mile of where solvents have been used (drycleaners, automotive garage, etc.) Test once every 5-10 years or if solvent or gasoline taste or odor is noticed.

Check with your local health department in order to determine if there are specific tests that are recommended for your community.

For more information on Private Well Water Testing Recommendations: US EPA – Private Drinking Water Wells


WI Dept. of Natural Resources. 2007. Tests for Drinking Water from Private Wells. WI Dept. of Natural Resources, Bureau of Drinking Water and Groundwater. PUBL-DG-023 2007.