Water Education
Well Water Testing: What to Test and When
Private well owners are responsible for their own water. What to test for each year, when to test again, and how to find a certified lab. Sourced from CDC and EPA.
If your home is on a private well, nobody else is testing your water. Here is what the CDC and EPA recommend and how to get it done.
You are responsible for your well
CDC explains that EPA rules protecting public drinking water systems do not apply to privately owned wells. Government officials do not regulate, treat, or monitor water from private wells. As the owner, you are responsible for testing your well (CDC, Guidelines for Testing Well Water). EPA’s private wells page offers more on protecting a household well (EPA, Private Drinking Water Wells).
Test every year for these
CDC recommends testing well water at least once a year for:
Total coliform bacteria. pH. Total dissolved solids (TDS). Nitrates. Other germs and chemicals of concern in your area (CDC).
These are mostly indicators. Coliforms are usually harmless themselves, but a high count suggests harmful germs may also be present. pH that is too low or too high can damage pipes, and damaged pipes can release metals such as lead into the water. TDS tells you how much dissolved material, such as calcium or sodium, is in the water, which affects taste and scale (CDC).
For reference, EPA’s non-enforceable secondary standard for TDS is 500 mg/L, set for taste and appearance rather than health (EPA, Secondary Drinking Water Standards).
Ask locally about other contaminants
What else to test for depends on where your well is, your state or region, and whether you are in a rural or urban area. CDC suggests asking your health or environmental department, or calling the EPA Safe Drinking Water Hotline at (800) 426-4791, about volatile organic compounds, lead, arsenic, mercury, radium, and pesticides or herbicides (CDC).
CDC notes that nitrates can come from animal waste, septic systems, fertilizers, farm runoff, and decaying plants, and that high nitrate levels can make people, especially babies, sick (CDC).
Test again when something changes
CDC recommends extra testing if:
You hear about well water problems in your area. There is flooding, land disturbance, or a waste site near your well. You replace or repair any part of the well system. The water’s taste, color, or smell changes. Someone in the home becomes pregnant, or a child comes to live with you (CDC).
CDC also suggests checking the well every spring for mechanical problems.
Use a certified lab
Use a state-certified laboratory. Local or state health departments often test for nitrates, coliforms, VOCs, and pH, and can point you to certified labs (CDC). EPA keeps a directory of state certification programs and certified drinking water labs (EPA, Certified Laboratories).
How to take a good sample
Follow the lab’s instructions exactly, because sample handling affects results. Labs usually supply sterile bottles for bacteria testing and set limits on how long a sample can sit before it reaches them. Ask your lab about bottles and timing. Take the sample from a cold water tap that does not pass through treatment equipment unless you are testing the equipment itself. Note the date, time, and tap you used, and keep your results so you can compare year to year.
After you get results
If results show harmful germs or chemicals, CDC advises considering bottled water or another safe source and contacting your local health or environmental department for next steps (CDC). For nuisance issues such as hardness or iron, a water treatment professional can help you choose equipment. WQA publishes questions to ask before you buy (WQA, Questions to Ask).
Sources
CDC, Guidelines for Testing Well Water (www.cdc.gov/drinking-water/safety/guidelines-for-testing-well-water.html)
EPA, Private Drinking Water Wells (www.epa.gov/privatewells)
EPA, Secondary Drinking Water Standards (www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals)
EPA, Certification Programs and Certified Laboratories (www.epa.gov/dwlabcert/contact-information-certification-programs-and-certified-laboratories-drinking-water)
Water Quality Association, Questions to Ask (wqa.org/learn-about-water/questions-to-ask/)
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