Well Water Testing: What to Test, How Often, and What It Costs

Well water testing belongs on your calendar once a year: send a sample to a state-certified lab for total coliform and E. coli, nitrate, pH and total dissolved solids, then add arsenic, lead, and local contaminants.

What should you test well water for?

Every well water testing plan starts with four annual basics from the CDC: total coliform bacteria (with E. coli if coliform shows up), nitrate, pH, and total dissolved solids. Then add arsenic and lead at least once, plus anything your county health department flags locally, such as uranium, radon, manganese, fluoride, pesticides, or PFAS near airports and industrial sites. If coliform turns up positive, shocking a well with bleach walks through disinfection and retesting, while well water versus city water weighs the ongoing responsibilities of managing your own supply. Weighing whether to stick with your current well or start fresh ties directly into well drilling cost. Before comparing drilling quotes, it’s worth checking whether iron buildup and staining is driving the decision to replace the well in the first place.

The basics are cheap screens for the most common failures. Coliform shows surface water or septic effluent getting in, nitrate tracks fertilizer and septic loading, and pH and TDS flag corrosive or mineral-heavy water.

Arsenic and lead are the two metals most homeowners skip and most often regret skipping. Arsenic comes from bedrock, so a well can be clean of bacteria and still fail. Lead usually comes from the plumbing itself: older brass fittings, solder joints, and submersible pump parts.

• Every year: total coliform and E. coli, nitrate, pH, TDS.
• At least once, then every few years: arsenic, lead, hardness, iron, manganese, fluoride.
• Where local geology or land use calls for it: uranium, radon, pesticides, volatile organics, PFAS.

How often should you test well water?

Test well water at least once a year for coliform, nitrate, pH, and TDS, the schedule both the CDC guidelines for testing well water and the EPA recommend. Test sooner after flooding, any well repair, a change in taste, color, or smell, a nearby septic failure, or a new baby or pregnancy in the house, since infants under 6 months are most sensitive to nitrate.

Spring is a smart time for the annual bacteria test. Some state health departments also suggest a broader panel every few years on top of the annual basics.

Any time the well is opened, retest. That includes pulling a pump, replacing a pressure tank, or switching between types of well pumps, because tools and pipe dropped down the casing can carry bacteria in with them.

Where do you get well water testing done?

Use a state-certified drinking water laboratory, not a store test strip. Every state runs a certification program, and the EPA keeps a directory of state certification programs and certified labs. Many county health departments sell sample kits, take drop-offs, and forward samples to the state public health lab for a fixed fee.

Certified labs use approved methods and detection limits low enough to read against EPA numbers. That matters for arsenic and lead, where limits sit in parts per billion.

Home kits have one fair use: a quick screen for hardness, pH, or iron between lab tests. A home strip that reads “no bacteria” or “lead safe” is not a result your lender, your health department, or your pediatrician will accept.

How much does well water testing cost?

A basic well water test for bacteria and nitrate through a public lab often runs about $40 to $61, based on published fee schedules from Maine CDC and Marathon County, Wisconsin. Single tests for arsenic or lead ran $35 to $52 at the Wisconsin county labs we checked, and broader home-sale panels ran $125 to $230. Private labs and regional prices vary.

Some health districts run free nitrate screening events, and a few states subsidize tests for new wells or for households with infants. Call your county environmental health office before paying a private lab.

How do you collect a well water sample?

Collect a bacteria sample from a cold-water tap with no aerator, disinfect the spout, run the water 2 to 3 minutes, then fill the sterile lab bottle without touching the inside or the faucet. Keep it cold and get it to the lab within 30 hours, per Wisconsin DNR coliform sampling instructions. A lead sample follows different rules.

1. Pick a day early in the week so the sample does not sit in a closed lab over the weekend.
2. Choose a cold-water tap that does not leak and is not a swivel or pull-out faucet. Skip any tap after a softener or filter unless the lab asks for treated water.
3. Remove the aerator, screen, or hose attachment.
4. Disinfect the end of the spout with isopropyl alcohol or unscented household bleach. Do not wipe it afterward.
5. Run the cold water at full flow for 2 to 3 minutes, then turn it down to a pencil-width stream for about 1 minute.
6. Uncap the bottle without touching the inside of the cap or the rim, fill to the line, and cap it right away. Do not rinse the bottle; many contain a preservative.
7. Label it, refrigerate if it will be more than a few hours before drop-off, and deliver within 30 hours.

Lead is the reverse. For lead, labs usually want a first-draw sample: water that sat in the pipes unused for at least 6 hours, often overnight, collected from the kitchen tap before anyone runs it. That method mirrors the one EPA uses for public systems, because it catches lead leaching from fixtures and fittings inside the house rather than from the aquifer.

How do you read well water test results against EPA limits?

Compare each result to the EPA Maximum Contaminant Level (MCL) listed in the National Primary Drinking Water Regulations. The limits legally bind only public systems, but they are the benchmark labs print on private well reports. Watch the units: mg/L equals parts per million, and µg/L equals parts per billion, 1,000 times smaller.

Bacteria results come back as present or absent. Any E. coli means the water is unsafe to drink until you fix and retest. Total coliform present with no E. coli means a pathway exists for surface contamination, even if the bacteria detected are not themselves harmful.

Hardness has no federal limit. The USGS classes water at 0 to 60 mg/L as calcium carbonate as soft, 61 to 120 as moderately hard, 121 to 180 as hard, and above 180 as very hard. Hard water is a scale and appliance issue, not a health issue.

Which regional contaminants should you add to a well water test?

Add tests based on what sits under and around your well. The USGS found inorganic contaminants such as radon and arsenic were the ones most often above health benchmarks in its private well study, and their spread follows geology. Your county health department is the best source for the local short list, and many publish maps of known problem areas.

For PFAS, EPA set enforceable limits of 4.0 parts per trillion for PFOA and PFOS in April 2024. Ask the health department about known PFAS sites before ordering that pricier test.

What should you do if your well water test fails?

Stop drinking the water for the failed contaminant and switch to bottled water for drinking, cooking, and infant formula. For bacteria, inspect the well cap and casing, shock-chlorinate the well, and retest once the chlorine is gone. For nitrate, arsenic, or lead, retest to confirm, find the source, and choose treatment rated for that contaminant.

A bacteria hit usually points to a physical defect. Look for a loose or vented cap without a screen, a cracked casing, ground that slopes toward the wellhead, or a septic field too close. Shock chlorination without fixing the entry point often fails again.

Chemical failures need treatment matched to the contaminant. A reverse osmosis system under the kitchen sink is the usual point-of-use answer for arsenic, nitrate, uranium, and lead in drinking water. Iron, manganese, sulfur smell, and sediment often call for a whole house water filter at the pressure tank so every fixture gets treated water.

Low pH needs its own fix. Corrosive water under 6.5 eats copper and brass, which raises lead and copper levels at the tap, so a calcite or soda-ash neutralizer may solve two failures at once. After treatment goes in, test water downstream of the equipment.

Is well water riskier than city tap water?

Well water is not automatically worse, but nobody else checks it. A city utility must test on a federal schedule under the Safe Drinking Water Act and report violations, while a private well owner gets no testing, no treatment, and no notice. That gap, not the water itself, is the main risk, which is why annual well water testing matters.

Studies cited by public health researchers show that, at best, about half of private well owners test with any regularity, and few test every year. If you are weighing the trade-offs on municipal supply, our guide on whether tap water is safe to drink covers what utilities test for and what they miss.