How to Test Your Well Water at Home Before Buying a Filter

To test well water at home, collect samples in sterile bottles from a state-certified laboratory and get them back to the lab within its hold time. The CDC’s baseline is to test a private well at least once every year for total coliform bacteria, nitrate, total dissolved solids (TDS) and pH. Then add extra tests based on your local geology, what is near the well and the age of your plumbing.

Nobody does this for you. The EPA does not regulate private wells or set standards for them, so the household is responsible for testing and for any treatment. This guide covers the annual tests, the sampling steps labs actually use, what testing costs at public labs, which extra tests fit which risks, and how to find a certified lab.

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The four tests every well needs each year

The CDC’s guidelines for testing well water name four annual tests, and the EPA’s private well guidance lists the same four:

The CDC also says to ask your local health department which other germs or chemicals are common where you live. Our breakdown of the main types of water quality tests explains what each category of lab panel covers.

When to test sooner than once a year

The CDC and EPA both call for an extra test, outside the yearly schedule, when:

• you hear about water problems in your area, or there is flooding, land disturbance, construction or a waste site near the well
• any part of the well system is repaired or replaced
• the water’s taste, color or smell changes
• someone in the home becomes pregnant, or an infant or child comes to live with you

The CDC also recommends checking the well for mechanical problems every spring.

How to collect a well water sample, step by step

Collection mistakes are the most common reason a test result comes back wrong. Always follow the instructions that come with your lab’s kit, because bottles, preservatives and deadlines differ between labs. The steps below are drawn from Penn State’s Agricultural Analytical Services Lab and the Kenosha County (Wisconsin) Public Health Laboratory, and they show what a typical kit asks for.

1. Get the bottles from the lab first. Bacteria samples go in a sterile bottle, and metals often need special containers the lab supplies. Do not substitute a jar from the kitchen. Some bottles contain a small white pill or powder. Leave it in.
2. Plan around the delivery deadline. Penn State requires bacteria samples to reach the lab within 30 hours of collection and asks that shipped coolers arrive no later than Thursday. Kenosha County asks for drop-off within 24 hours, with ice still in the cooler. So collect early in the week and close to when you can ship or drive the sample in.
3. Take any first-draw samples before running the water. Lead and arsenic samples are usually “first draw.” Water should have sat in the pipes for at least six hours (Kenosha County says 6 to 12 hours for arsenic), so collect first thing in the morning from a cold-water kitchen or bathroom tap. Do not use the pressure tank, an outdoor spigot or a laundry tap.
4. Prepare the tap for the bacteria sample. Use an inside faucet and remove the aerator.
5. Flush the line. Run cold water for about five minutes. This clears water that has been sitting in the plumbing and draws fresh water from the well. If the well was recently chlorinated, keep pumping until the water is free of chlorine, or the bacteria result will be meaningless.
6. Fill without touching the inside. Hold the cap by its outside and do not touch the inside of the bottle or cap. Fill the bacteria bottle to the marked line (often 100 mL) and close it tightly. Do not rinse a sterile bottle. Some labs do ask you to rinse the separate chemistry bottle, so check your instructions.
7. Record the details. Write down the date and time, which tap you used, and whether the water passed through a softener or filter. Rhode Island’s state lab form asks for all of these.
8. Keep it cold and get it to the lab. Refrigerate or ice the samples until delivery, then ship or drop them off within the lab’s hold time.

One special case: hydrogen sulfide (the rotten-egg odor) escapes from a sample quickly. Penn State Extension says it must be tested in the home or chemically stabilized before going to a lab. If odor is your problem, see our guide on getting rid of rotten egg smell in well water.

What well water testing costs

Public labs post their fees, so you can price a test before you order. The figures below come from current published fee schedules. Private certified labs set their own prices, so ask for a written quote for the same tests before comparing.

Home strips can flag an obvious change, but the CDC and EPA both tell well owners to use a state-certified laboratory. A strip that reads “safe” for bacteria is not the result you want to rely on for a newborn or for a decision about treatment equipment.

Extra tests by risk

The four annual tests miss many contaminants. The CDC notes that testing can be expensive, so figure out which problems are likely before ordering more. The EPA’s private well guidance and state health agencies tie extra tests to specific conditions:

If PFAS is the concern, our guide to PFAS in drinking water explains sources and which filter certifications matter. If you also rely on a cistern or roof catchment, our off-grid well and rainwater contamination guide covers the different risks.

How to find a state-certified lab

1. Start with your local or state health department, or your county. The CDC says these offices can give you a list of certified labs. Some health departments offer free or low-cost private well testing, and many county labs (like Kenosha’s) take samples directly.
2. Use EPA’s lab certification directory. EPA does not test residential water on request. Its drinking water lab certification page lists each state’s certification program, and those programs publish their certified labs.
3. Call the EPA Safe Drinking Water Hotline, (800) 426-4791, for help deciding which contaminants to test for where you live.
4. Confirm the lab is certified for each test you order. Certification is by analyte and method, so a lab certified for bacteria may not be certified for PFAS or uranium.

What to do with the results

Compare each number against the standard printed on the report, or ask your health department to help you read it. A few results call for action right away:

• Coliform positive: stop drinking the water and use bottled water or water boiled for one minute. Disinfect the well and retest before you drink it again. Mississippi State Extension’s shock chlorination procedure ends with a certified lab test before the water is used for drinking or cooking.
• Nitrate above 10 mg/L: use a safe alternative source, especially for infant formula, and do not boil the water. Boiling concentrates nitrate (see what boiling water does not remove). Minnesota recommends having a licensed well contractor inspect the well.
• Arsenic above 10 ppb or uranium above 30 ppb: Massachusetts recommends a follow-up test, then treatment if it is confirmed. Usually only drinking and cooking water needs treating, with reverse osmosis, anion exchange or adsorptive media.

Then match the treatment to what the lab actually found. Our comparison of the best water filters for well water sorts systems by iron, sulfur, bacteria and PFAS. Look for independent certification against the specific contaminant on your report.

Frequently Asked Questions

How often should I test my well water?

At least once a year for total coliform bacteria, nitrate, TDS and pH, according to the CDC. Test again after flooding, well repairs, a change in taste, color or smell, or when someone in the home becomes pregnant or a baby arrives.

Can I test well water myself with a home kit?

You can screen with strips or a TDS meter, but they do not replace a lab result. The CDC and EPA tell private well owners to use a state-certified laboratory. You collect the sample yourself at home, and the lab runs the analysis.

How much does a well water test cost?

At public labs, the annual basics are modest. Kenosha County, Wisconsin charges $35 each for bacteria and nitrate, and Rhode Island’s state lab sells an annual kit for $95. Add-ons cost more: Wisconsin’s state lab lists a VOC screen at $141, and Rhode Island lists PFAS at $200.

What is the best time of year to test a well?

The CDC recommends checking the well for mechanical problems every spring, which makes spring a natural time for the annual test. Testing after events like flooding or repairs matters more than the calendar.

Does a clean bacteria test mean my water is safe?

It means coliform bacteria were not found in that sample. It says nothing about nitrate, arsenic, uranium, lead, VOCs or PFAS, which need their own tests based on your well’s risks.

Sources

• CDC — Guidelines for Testing Well Water
• U.S. EPA — Protect Your Home’s Water (private wells)
• U.S. EPA — Certification Programs and Certified Laboratories for Drinking Water
• U.S. EPA — PFAS and Private Wells (fact sheet, April 2025)
• U.S. EPA — Sources of Lead
• Penn State Agricultural Analytical Services Lab — How to Collect a Water Sample
• Kenosha County Public Health — Private Well Water Tests
• Wisconsin State Laboratory of Hygiene — Public Environmental and Water Testing Prices
• Rhode Island Department of Health — Private Well Laboratory Test Request Form
• USGS — Arsenic and Uranium in Private Bedrock Wells, East-Central Massachusetts (SIR 2011-5013)
• Massachusetts — Arsenic and Uranium Bedrock Well Study FAQs
• Minnesota Department of Health — Nitrate in Drinking Water
• Minnesota Department of Health — Hydrogen Sulfide in Well Water (testing schedule)
• Penn State Extension — Hydrogen Sulfide (Rotten Egg Odor) in Water Wells
• Mississippi State University Extension — Disinfecting a Water Well Through Shock Chlorination

Last updated October 31, 2026.

This article is for general information only. For questions about a specific result or a health concern, contact your state or local health department or your physician. See our Health Disclaimer.