Testing Guide

How to Test Your Private Well Water

Private wells have no required testing — that responsibility falls entirely on you. Here's what to test for, how to do it, and how to make sense of your results.

What should I test for?

Start with the core panel. These are the contaminants most likely to affect private wells across the US:

  • Total coliform and E. coli — the most important test. Bacteria in well water is a health emergency.
  • Nitrate — especially important if you have infants or are pregnant. Agricultural areas are higher risk.
  • Arsenic — naturally occurring in bedrock across the northern and western US. Colorless and odorless.
  • Lead — less common in well water itself, but can leach from older plumbing into your tap.
  • pH and hardness — affects how your water tastes and how hard it is on pipes and appliances.
  • Iron and manganese — common in well water. Stains laundry, affects taste. Not an acute health risk but worth treating.

If you live near farms, mining operations, or industrial sites, also test for pesticides, heavy metals, and volatile organic compounds (VOCs).

If you've never tested your well, or moved into a home with a well, get a comprehensive panel. Don't guess.

How often should I test?

  • Bacteria (coliform/E. coli): every year, or after flooding, power outages, or any work on the well
  • Nitrate: every year if you have infants or are pregnant; otherwise every 2–3 years
  • Arsenic, heavy metals, other contaminants: once as a baseline; again if you notice changes in taste, odor, or color
  • Full panel: whenever you buy a home with a well or install a new well

How do I collect a sample?

Your lab will send sterile bottles with instructions. The general steps:

  1. Remove any aerators or filters from the tap — you want raw well water
  2. Run cold water for 2 minutes to flush the lines
  3. Fill the lab's bottles without touching the inside of the cap or bottle neck
  4. Keep samples cold and ship within 24 hours (most labs include a pre-paid cold pack)

Follow your lab's specific instructions exactly. Bacteria samples in particular are time-sensitive.

How do I read my lab report?

Your report will list each contaminant with a detected value and the EPA's Maximum Contaminant Level (MCL). Here's what the numbers mean:

  • ND (not detected) — the contaminant wasn't found at any measurable level. Good.
  • Below MCL — detected, but below the safety limit. Worth monitoring.
  • Above MCL — exceeds the EPA limit. Treatment is recommended.

Not sure what your numbers mean? Use our result interpreter to classify your result →

Ready to test your well?

Tap Score is our recommended certified lab for private well owners. Their well water panel covers bacteria, nitrate, arsenic, lead, and more — with clear, plain-language results delivered online.

Order a Tap Score well water test kit →

You can also use a state-certified lab — see the Lab Finder tab for options in your state.

Municipal water is tested — but not at your tap

If you're on a public water system, your utility is required by law to test the water leaving the treatment plant and report results annually in a Consumer Confidence Report (CCR). You can request your CCR from your water utility or find it on the EPA's website.

What the CCR doesn't tell you: what happens between the treatment plant and your tap. Lead can leach from older service lines and home plumbing. If your home was built before 1986, consider testing your tap water for lead specifically.

How to get your CCR

Contact your water utility directly and ask for the most recent Consumer Confidence Report. By law, they must provide it. You can also search the EPA's CCR database at epa.gov.

Should municipal users test their tap?

Testing is optional for municipal users but worth considering if:

  • Your home was built before 1986 (lead plumbing risk)
  • You have corroded or discolored pipes
  • Your utility has issued any boil-water advisories in the past year
  • You notice changes in taste, color, or odor

A point-of-use filter certified to NSF/ANSI 53 for lead is a reasonable precaution for older homes regardless of test results.

Finding a certified lab in your state

For health-related testing (arsenic, nitrate, bacteria, lead), use a state-certified laboratory. Certification ensures the lab follows EPA-approved methods and their results hold up if you ever need to take action.

How to find a certified lab

  • State health department: most states maintain a list of certified labs. Search for "[your state] certified drinking water laboratory" or contact your state health department directly.
  • EPA's lab locator: the EPA maintains a directory of certified labs at epa.gov/dwlabcert. Search by state and analyte.
  • Cooperative Extension: many land-grant universities run water testing programs for private well owners at reduced cost. Search "[your state] cooperative extension water testing."

Mail-in options

If you prefer to order online and ship your sample:

  • Tap Score — certified private-label lab testing with plain-language results. Recommended for well owners who want a clear report without decoding lab jargon.
  • National Testing Laboratories — long-established mail-in lab for well water.
  • Your state extension program — often the lowest-cost option for basic panels.

Order a Tap Score test kit →

What to ask for

When contacting a lab, ask for a private well water panel or specify: total coliform, E. coli, nitrate, arsenic, lead, pH, hardness, iron, and manganese. A comprehensive panel typically runs $150–$300 depending on the lab and number of analytes.