Private Well Water Safety

If your home uses a private well, there is no water utility testing or treating your water. In the United States, the EPA regulates public water systems, but not private wells, so the owner is responsible for keeping the water safe. Many contaminants have no taste, color or smell, so the only way to know is to test.

• Homeowners
• Rural Families
• Renters & Landlords

Where contamination comes from

• Natural sources: arsenic, radon, uranium, fluoride, iron, manganese and other minerals in the rock and soil.
• Bacteria and viruses: from septic systems, animal waste, flooding and damaged well casings. Coliform bacteria and E. coli signal possible contamination. See Septic System Safety.
• Nitrates: from fertilizer, septic systems and manure. They are especially dangerous for infants under six months, since they can cause “blue baby syndrome” (a drop in the blood’s oxygen). Boiling doesn’t remove nitrates and concentrates them.
• Chemicals: pesticides, solvents, gasoline and oil from leaks or spills, road salt, and industrial or landfill pollution. See Household Chemicals.
• Lead and copper from household plumbing, especially with acidic water. See Lead in Drinking Water.
• Radon in water can enter indoor air when you shower or run water. See Radon.
• Emerging contaminants such as PFAS in some areas.

Test your water

• Test at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH. These are the common basic tests recommended by public health agencies.
• Test more often or for more things if there is a baby or pregnant person in the home, someone has recurring illness, the water has changed taste, color or smell, the well is shallow, there is a nearby septic system, farm, gas station or landfill, or after flooding, repairs or construction.
• Test for local risks such as arsenic, radon, uranium, lead, pesticides, volatile organic compounds and PFAS, as your health department or geologic survey advises.
• Use a state-certified lab. Ask your local health department or state drinking water program for a list, collect samples exactly as the lab says, and bring them quickly. Home test kits are less reliable for many contaminants.
• Keep records of test results, well maintenance and repairs, and compare year to year.
• Test new wells before use, and when buying a home with a well. See Hiring Contractors for well work.

Protect the well

• Check the wellhead. The well casing should extend above ground (and above the flood level where possible), with a tight, sanitary cap or seal and a screened vent. Slope the ground away from the well so water drains away.
• Keep hazards away. Don’t store or mix pesticides, fertilizer, fuel, paint, solvents or manure near the well. Know the legal setback distances from septic tanks, fields, livestock areas and chemical storage (they vary by area).
• Maintain the septic system and keep it away from the well. See Septic System Safety.
• Hire licensed professionals for drilling, repairs, pump work and abandonment. Old, unused wells should be properly sealed by a licensed contractor, since they can carry contamination to groundwater and are a safety hazard for children and pets.
• Inspect regularly, looking for cracks in the casing, a loose or missing cap, standing water and pump problems.
• Be careful with lawn and garden chemicals and fuel near the well. See Using Pesticides at Home.

After a flood, storm or problem

• Flooded wells: don’t drink the water. Floodwater can carry bacteria, sewage and chemicals into the well. Use bottled or boiled water until the well has been disinfected and tested. See Hurricanes & Floods.
• Disinfect (shock chlorinate) the well and plumbing as your health department or a licensed contractor directs, then retest after flushing. Follow the exact directions, since too much or too little bleach is ineffective or dangerous. Turn off the power to the pump first, and take care around electricity. See Disaster Cleanup.
• Power outages stop the pump, so plan for water. See Power Outages & Generators.
• Change in taste, smell, color or cloudiness, or sudden illness in the household? Stop drinking the water and test it.

When to boil water

• If a test shows bacteria, or you are advised to disinfect, bring water to a rolling boil for at least 1 minute (3 minutes at elevations above 6,500 feet), cool it and store it in clean covered containers.
• Boiling kills germs, but doesn’t remove chemicals, nitrates, arsenic or lead, and may concentrate some of them.
• Use boiled or bottled water for drinking, making ice, brushing teeth, washing food, preparing baby formula and pet water.

Treatment options

• Pick treatment systems certified to NSF/ANSI standards for the specific contaminant, and maintain filters and lamps as directed. Neglected filters can make water worse.
• Treatment is not a substitute for finding and fixing the source of contamination. Retest after installing treatment, and every year.
• Be skeptical of door-to-door sales and scare tactics. Get your own lab test first.

Well water checklist

• I test my well at least every year for coliform bacteria, nitrates, pH and dissolved solids, plus local risks
• The wellhead has a sealed cap, the ground slopes away, and no chemicals or fuel are stored nearby
• My septic system is maintained and kept away from the well
• After flooding or any problem, I use bottled or boiled water until the well is disinfected and retested
• Treatment systems are certified, maintained and tested
• I keep records, and unused wells are properly sealed

Last updated: October 5, 2026