How to Test Well Water: What to Test For, Where, and How to Read Results

What to test your well water for every year

The CDC says to test your well water at least once each year for total coliform bacteria, nitrates, total dissolved solids, and pH. The EPA gives the same four tests in its guidance for private wells. Those four are the baseline panel because you cannot taste, see, or smell most of what they find. Coliform shows that something from the surface is reaching the water. The EPA lists fertilizer runoff and leaking septic tanks as sources of nitrate. The pH and total dissolved solids readings describe the water chemistry, which affects your pipes and the taste.

Nitrate matters most when there is a baby in the house. The EPA says infants below the age of six months who drink water with nitrate above the limit could become seriously ill, with shortness of breath and blue-baby syndrome. Well treatment is for bacteria, so a high nitrate result calls for a different plan, and your health department can advise you on treatment or another water source.

When to add more tests

The Minnesota Department of Health recommends coliform and nitrate every year, and arsenic, lead, and manganese at least once. The Florida Department of Health says most homeowners should test for lead every three years. The EPA says heavy metals such as lead can leach into drinking water from household plumbing, so a new well does not rule lead out. The EPA says to test well water for radionuclides, such as uranium, radium, and radon, every three years, because they come from the rock and soil around the well. Test for fuel and solvent chemicals when a spill, a buried fuel tank, or a waste site is near the well, which the EPA lists as ways these chemicals reach private wells.

For PFAS, an EPA fact sheet from April 2025 says the EPA does not regulate or set standards for private wells, and tells owners to ask their state environmental or health agency for advice and a list of certified labs. The federal PFOA and PFOS limits in the table below apply to public water systems. The best single question to ask your county or state health department is which tests they recommend for wells in your area.

Well water test table: what, why, how often, and the standard

An MCL is a maximum contaminant level, which the EPA defines as the highest level of a contaminant allowed in drinking water and enforces for public water systems. A secondary standard covers taste, odor, color, and staining, and the EPA does not enforce it. Neither one is a legal requirement for a private well, but labs and health departments use both as the yardstick.

When to test outside the yearly schedule

The CDC lists six times to test beyond the yearly panel:

• You hear about problems with well water in your area.
• There is flooding, land disturbance, or a waste disposal site near your well.
• You replace or repair any part of the well system.
• You notice a change in the taste, color, or smell of the water.
• You or someone you live with becomes pregnant.
• A child starts living with you.

The EPA adds that homes with small children, older adults, or a pregnant or nursing person may need more frequent tests. If the water tastes or smells wrong, our guides on staining and a metallic taste help you decide which tests to add.

How to find a state-certified lab

Both the CDC and the EPA say to use a laboratory that is certified for drinking water testing. The EPA keeps a page of state certification programs and certified laboratories, with a link to each state's program and its list of labs. The EPA does not test water for homeowners itself. In practice, start with your county health department, which often sells the bottles and runs the test, then the state list, then the county extension office, which runs well testing clinics in many states. Our answer on where to get your well water tested has the short version.

What a well water test costs

Prices depend on the state and the panel. The Florida Department of Health says county testing is usually $20 to $30 per sample, plus $30 to $40 per visit when a health department employee collects the sample at your home. The Vermont Department of Health Lab lists $14 for its bacteria kit, $100 for its inorganic chemicals kit, which includes nitrate, uranium, and fluoride, and $45 for gross alpha radiation. A wide panel from a private lab costs more. Ask the lab for the price of each test before you order, and ask whether your county has a subsidized program for private wells.

Well water testing cost at a glance

The ranges come from the Florida Department of Health and The Well Guide's testing cost guide (updated October 2026), a commercial cost guide. Prices vary by state and lab, so ask for the price of each test before you send a sample.

Where can I get my well water tested for free?

Free testing exists, but it is local and it changes from year to year. Work through it in this order:

1. Call your county health department. Ask whether it tests private wells, what it charges, and whether there is a free or subsidized program this year.
2. Ask your state health department or state well program. Some states fund free tests where a problem is common. The Minnesota Department of Health funds free certified tests for private wells in eight southeast Minnesota counties, for nitrate, arsenic, bacteria, lead, and manganese, with kits mailed to the home while supplies last.
3. Ask your water district or county extension office. Santa Clara Valley Water in California collects free samples from eligible domestic wells, and extension offices in many states run well testing clinics.
4. Look for a rural water nonprofit. The Rural Community Assistance Corporation offers free well assessments and nitrate screening in parts of the western states it serves.

If none of these apply, the EPA's list of state certification programs leads to the certified labs in your state, and the cost table above shows what to expect.

Mail-in well water test kits

A mail-in kit from a certified lab is a set of sample bottles, a form, and a return box. You collect the sample at home and ship it back, and the lab runs the test. Bacteria samples need care: the lab sets the days it accepts them, and Colorado State University Extension says the sample must stay cool and reach the lab within 24 hours. That means overnight shipping, early in the week. Chemical tests such as nitrate, metals, and PFAS are less time-sensitive, but follow the lab's bottle and holding rules. Use a lab certified for drinking water in your state, so the result counts for a health department or a lender.

What to do if the bacteria test is positive

Stop drinking the water untreated and use bottled water. Check the wellhead for a loose cap, cracks, or standing water. Then disinfect the well and retest in one to two weeks, as Colorado State University Extension advises. An E. coli positive is the more serious result; our E. coli guide covers what to do the same day. Our guide on how to treat a well walks through the treatment, and our well treatment kit is sized to your well, with a bacteria test for before and after. The well disinfection calculator gives the gallons in your well first.

How to collect a well water sample

The lab's instructions come first, because each test has its own bottle and rules, and some bottles hold a preservative. The steps below are the common ground among the Colorado State University Extension, the Vermont Department of Health, and the Minnesota Department of Health.

1. Call the lab before you sample. Labs accept bacteria samples only on set days, and many do not accept them late in the week.
2. Pick a cold-water faucet that is in regular use. Colorado State University Extension advises a faucet with the aerator removed and says kitchen faucets with swivel arms are not recommended.
3. Clean the faucet opening the way the lab says. Vermont tells you to sanitize the faucet with rubbing alcohol for its bacteria bottle.
4. Run the cold water. Colorado State University Extension says to run it at full flow for three minutes, then at a trickle for one more minute.
5. Wash your hands, open the bottle, and fill it without touching the inside of the bottle or the cap. Do not rinse the bottle.
6. Cap it tightly and label it with your name, address, and the date and time.
7. Keep the sample cool and get it to the lab within 24 hours, which is the Colorado State University Extension rule. Vermont says to drop off or ship the sample the same day you collect it.

If you have a softener or filter, decide which water you want to know about. The Minnesota Department of Health says to test the water after it goes through treatment, because that is the water you drink. A sample from a faucet before the treatment tells you about the well itself. Many owners test both.

How to read the result sheet

Bacteria results come back in one of two forms. Most labs report total coliform and E. coli as present or absent. Some report the number of organisms detected per 100 milliliters, and some only mark the sample safe or unsafe, according to Colorado State University Extension. The EPA says total coliform is not a health threat in itself, and labs use it to show whether other harmful bacteria may be present. The EPA also says E. coli comes only from human and animal fecal waste, so an E. coli positive is the more serious result. Use bottled water and ask your health department what to do next.

Colorado State University Extension says that a result above 1 total coliform per 100 milliliters, or a result marked unsafe, means you should disinfect the well and retest in one to two weeks. The EPA treats any total coliform detection in a public system as a result to act on, and our coliform guide follows that stricter reading. If the bacteria come back, the source must be found and fixed. Our positive coliform test page explains the result in plain words, and the coliform guide covers the wellhead check and the treatment.

For chemicals, compare each number to the standard in the table above. A result above an MCL, such as nitrate above 10 mg/L or arsenic above 0.010 mg/L, is a health question for your health department and a treatment question for a water treatment professional. A result above a secondary standard, such as iron above 0.3 mg/L, is a taste, color, or staining problem, which the EPA does not enforce. Keep every result sheet. A record over the years shows you when something changes, and our page on whether well water is safe to drink explains why the record matters.

Home test kit or certified lab?

A home test gives you a quick screening result. A certified lab gives you a result that a health department, a lender, or a doctor can use. The CDC and the EPA both tell well owners to use a state-certified laboratory, so use the lab when the result decides something: a home sale, a pregnancy or an infant in the house, an illness, or a treatment purchase.

Our treatment kit ships two presence or absence coliform tests, one for before the treatment and one for 7 to 14 days after, plus Selectrocide chlorine dioxide pouches sized to your well. Those two tests tell you whether coliform was detected in each sample. They do not measure nitrate, metals, or any other chemical, and they are not a substitute for the yearly certified lab panel above. We also have a well water test kit page for owners who want to start at home.

Well water testing for a home sale

The rules come from the lender and from the state or county, so ask both before you order a test. For an FHA loan, the HUD Handbook 4000.1 (January 18, 2023 revision) says the water must meet the requirements of the local health authority, or EPA primary drinking water standards where there is no local or state standard. It requires a well water test for newly built homes, when the appraiser reports a problem with the well or the water, when the water is known or reported to be unsafe, and near dumps, landfills, industrial sites, or farms. A disinterested third party must collect and test the sample, and the buyer or the owner may never collect or transport it. When a test is required, the report may be up to 180 days old at disbursement.

Some states require a test at every sale. The New Jersey Department of Health says the state's Private Well Testing Act requires testing of raw, untreated water from private wells whenever a property is sold by contract. VA and conventional lenders set their own conditions, so get the lender's list in writing. To pass, test early, before the closing date is close. If coliform is present, find and seal the entry point, disinfect the well, flush it, and retest with a certified lab. Our guide to well inspection when buying a house covers the rest of the sale, and your state's page has the record of the well itself.