Well Water Testing Basics

Why do private wells need testing?

Public water systems are tested and regulated. Private wells generally are not, so the owner decides when and what to test. Water can look, smell, and taste fine and still carry bacteria, nitrate, or natural minerals like arsenic that you cannot detect without a lab.

CDC and EPA guidance for well owners both stress testing on a regular schedule and after certain events.

A well also changes over time. Pumps wear, casings corrode, and land use nearby shifts, so a test that was clean ten years ago may not describe your water today.

When should you test your well?

A common starting point in public health guidance is a yearly test for bacteria, with more tests depending on your area and your household. Test sooner if something changes, and keep the results in one file so you can compare years.

Ask your state or local health department and your extension office for the schedule recommended where you live.

Know your well. Write down its depth, age, location, and the name of the contractor who drilled or serviced it if you can find them. Records from the state or county may exist, and they help advisers judge what risks your water might face.

• A change in taste, color, smell, or clarity
• Flooding or standing water around the wellhead
• Nearby spills, construction, or new septic work
• Repairs or work on the well or pump
• A new baby, pregnancy, or someone in the home with a weakened immune system
• After buying a home with a well

What should you test for?

A basic panel usually includes coliform bacteria, nitrate, pH, and total dissolved solids. Beyond that, what matters depends on your local geology and land use: some regions have naturally occurring arsenic or radon, while farm areas may call for pesticide or nitrate checks.

Your health department or extension office often knows what has turned up in your county. Ask them what is worth testing for at your location.

If you have livestock, a fuel tank, a pesticide shed, or an old septic system near the well, tell your adviser. Those details help them recommend extra tests that a basic panel would miss.

How do you collect a sample properly?

Use a sterile bottle and the instructions from the lab, and follow them exactly. Labs generally tell you which tap to use, how long to run the water, how to keep the bottle from being touched inside, and how to keep the sample cold and get it to them within a time limit.

A mistake in collection can produce a false result, so if you are unsure, call the lab and ask before you start.

Plan the day around the lab's hours. Many labs want samples on certain days so they can start the test within the holding time, and you do not want a sample sitting in a hot car.

Where do you send the sample?

Use a laboratory that is certified for drinking water testing in your state. Your state health or environment department can list them, and many extension offices run or recommend testing programs. Do not use a lab that cannot tell you its certification.

Keep a bottled or otherwise safe supply on hand while you wait for results if the test was prompted by illness or a flood. Ask your health department what to use for drinking and cooking in the meantime, and follow their advice about when it is safe to switch back.

What do you do with the results?

Compare the numbers to the health-based standards the lab reports, and ask your health department or extension office to help interpret anything unfamiliar. If bacteria are found, ask the health department what to do about drinking and cooking water in the meantime and how to retest.

If a result is above a health limit, do not guess at a fix. Treatment depends on the problem, and the wrong equipment can fail to help or make things worse.

Share the results with your household and write the next test date on the same page. A report that nobody remembers is of little use.

• Keep every report with its date
• Ask for help reading results you do not understand
• Follow health department advice on safe drinking water while you fix a problem
• Retest after any repair or treatment

How do you protect your well between tests?

Keep chemicals, fuel, manure, and animal waste well away from the wellhead, make sure the cap is secure, and keep the area around it graded so water runs away. Septic systems, livestock yards, and fertilizer storage should be kept at a safe distance, and local rules set minimums that vary. A licensed well contractor can inspect the well and recommend repairs.

Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.