How to test your well water

By Well & Tap ResearchUpdated September 27, 2026How we research

Short answerSend a sample to a state-certified lab at least once a year for total coliform bacteria, nitrate, pH and total dissolved solids, which costs about $60 to $70 at a university lab. Before buying any treatment, add iron, manganese, hardness and whatever your health department flags for your area, such as arsenic, lead or PFAS.

Test a private well at least once a year for total coliform bacteria, nitrate, pH and total dissolved solids (TDS), using a state-certified laboratory. That is the baseline both the CDC and EPA recommend, and it costs about $60 to $70 at a university lab.

Everything beyond that depends on where you live and what you plan to do with the results. If you are about to buy a filter or softener, test for the things that equipment is sized around, because guessing is how people end up with a $2,500 system that fails in six months.

Why testing is your job

EPA’s rules for public water systems do not cover private wells. As EPA puts it, government officials “do not regulate, treat, or monitor” water from a private well, so the owner is responsible for knowing what is in it.

It is not a hypothetical risk. A USGS study of more than 2,000 domestic wells in 30 major aquifers found about 23% had at least one contaminant above a human-health benchmark. Radon, nitrate, several trace elements, fluoride, radioactivity and fecal indicator bacteria were the most common problems.

What to test for

Every year

Test	Why
Total coliform bacteria (with E. coli)	Shows whether surface water or sewage can reach the well
Nitrate	Comes from fertilizer runoff and septic systems; dangerous for infants
pH	Low pH corrodes pipes and can pull lead and copper into the water
Total dissolved solids	A general check that flags changes worth investigating

Based on what is near your well

EPA publishes a short list that matches nearby activity to extra tests:

If your well is near	Add tests for
Farms or orchards	Nitrate, nitrite, pesticides, coliform bacteria
Gas drilling	Chloride, sodium, barium, strontium
Mining	Metals, pH, corrosion
Industrial or commercial sites	Volatile organic compounds, TDS, pH, sulfate, chloride, metals
Old plumbing with lead parts	pH, lead, copper
Areas with radon in soil	Radon

Call your county or state health department and ask what it recommends for your area. Arsenic, uranium and radon follow the local geology, and the health department will know if they show up nearby.

Before you buy treatment

Treatment equipment has hard limits, so test for the numbers it is sized around:

Iron and manganese. Most iron filters are rated by parts per million of iron. Salt-free conditioners typically need iron below 0.3 mg/L and manganese below 0.05 mg/L.
Hardness. Softeners are sized in grains; divide the lab’s mg/L result by 17.1 to get grains per gallon.
Hydrogen sulfide. The rotten egg gas escapes from an open bottle, so ask the lab how to sample for it.
pH and alkalinity. Many oxidizing filters and softeners list a minimum pH.
Tannins, if your water is tea-colored.

Some sellers require this. SpringWell will not ship its WS1 well filter until a $134.25 water test comes back compatible. If you are shopping, our best whole house filters for well water page lists each system’s limits.

PFAS

Test for PFAS if your well is near a known or suspected PFAS source, such as a site where firefighting foam was used, a landfill or a factory that used PFAS. Connecticut’s environmental agency says a certified lab test typically costs “$300 or more per sample,” recommends EPA Method 533 because it covers more compounds, and expects results in two to three weeks. Its view is that testing is not generally needed unless a source is nearby.

When to test

Test once a year as routine. Test again right away, according to the CDC and EPA, when:

There is flooding or land disturbance near the well, or new construction or industry nearby.
You replace or repair any part of the well system.
The water’s taste, color or smell changes.
Someone in the home becomes pregnant or a baby joins the household.
Neighbors or the health department report groundwater problems in your area.

Certified lab or home kit

Use a state-certified laboratory. The CDC says your local health department “should have a list of the state-certified (licensed) laboratories in your area,” and EPA keeps a directory of state lab certification programs. EPA’s Safe Drinking Water Hotline is 800-426-4791.

Mail-in kits from private companies can be fine, as long as the lab doing the analysis is certified in your state for each test you order. Check before you pay.

Test strips and color kits are useful for quick checks of hardness, pH, chlorine or iron between lab tests, or to see whether a new filter is working. They are not a substitute for a certified lab when the question is whether water is safe to drink. No strip can measure PFAS at the parts-per-trillion level EPA regulates.

What testing costs

University and state labs publish their prices, which makes them a useful benchmark.

Lab	Test	Price
Penn State AASL	Standard: coliform, E. coli, pH, TDS	$60
Penn State AASL	Agriculture/septic: standard plus nitrate	$70
Penn State AASL	Aesthetics/corrosivity: adds hardness, alkalinity, corrosivity, copper, iron, manganese	$85
Penn State AASL	Same plus first-draw and running lead	$125
Penn State AASL	Extensive: bacteria, metals, nitrate and more	$220
Wisconsin State Lab of Hygiene	Bacteria (coliform and E. coli)	$35
Wisconsin State Lab of Hygiene	Nitrate	$35
Wisconsin State Lab of Hygiene	Arsenic or lead	$38 each
Wisconsin State Lab of Hygiene	Homeowner package: bacteria, nitrate, nitrite, fluoride, metals, hardness, VOC and atrazine screens	$450
Any certified lab (Connecticut estimate)	PFAS	$300 or more

Penn State prices were checked September 2026; Wisconsin’s took effect July 1, 2026. County health departments often run cheaper bacteria and nitrate tests, so ask there first.

How to take a good sample

Follow the lab’s instructions exactly, because a bad sample gives a bad result.

Use the lab’s bottles. Bacteria bottles are sterile. Do not rinse them or touch the inside of the cap.
Mind the clock. Under federal drinking water rules, a coliform sample must reach incubation within 30 hours of collection. Collect early in the week and ship or drop it off the same day.
Pick the right tap. To size treatment, sample raw water before any filter or softener. To check a filter, sample after it.
Follow lead instructions. Lead tests often use a first-draw sample after water has sat overnight, which is why Penn State’s lead package tests both first-draw and running water.

How to read the results

Labs report in mg/L (the same as parts per million), µg/L (parts per billion) or ng/L (parts per trillion). Compare each number with EPA’s limits. Primary limits protect health. Secondary limits cover taste, staining and odor.

Result	EPA limit or goal	What it means
E. coli	Health goal of zero	Fecal contamination. Do not drink the water untreated; call the health department
Total coliform	Health goal of zero	A pathway into the well. Inspect the well cap and casing, disinfect, retest
Nitrate (as N)	10 mg/L	Health limit set to protect infants under six months
Arsenic	0.010 mg/L	Health limit
Lead	0.015 mg/L action level, falling to 0.010 mg/L on Nov 1, 2027	Usually from plumbing; low pH makes it worse
Uranium	30 µg/L	Health limit
Fluoride	4.0 mg/L	Health limit
PFOA, PFOS	4 ng/L (ppt) each	2024 limits, in force until EPA finalizes changes
Iron	0.3 mg/L (secondary)	Rusty color, metallic taste, orange stains
Manganese	0.05 mg/L (secondary)	Black staining, bitter taste
pH	6.5 to 8.5 (secondary)	Outside this range, corrosion or scale
TDS	500 mg/L (secondary)	Hardness, deposits, salty taste
Sulfate	250 mg/L (secondary)	Salty taste

Hardness has no EPA limit. USGS classifies 0 to 60 mg/L as soft, 61 to 120 as moderately hard, 121 to 180 as hard and above 180 as very hard.

Bacteria first

If a sample shows coliform bacteria, fix that before you shop for filters. The source is usually a damaged well cap, casing or seal, and a UV lamp downstream does not repair the well. Your health department can walk you through disinfection and a retest.

When to call a pro

Call your county or state health department to interpret any result above a health limit. They answer these questions daily and often know the local cause.

Call a licensed well contractor if coliform keeps coming back after disinfection, if the cap or casing is damaged, or if a flood reached the wellhead. Call a water treatment professional once you have results in hand, and get a written quote that names the equipment’s limits for iron, hardness and pH.

What to do with the results

Match each problem to its fix:

Orange stains or metallic taste: iron in well water.
Rotten egg smell: sulfur smell in well water.
Hard water and scale: salt-free vs salt water softener.
PFAS detected: how to remove PFAS from water.

If more than one problem shows up, the order of equipment matters: sediment filter first, then the iron and sulfur filter, then the softener, with UV last. Our well water filter picks are sorted by problem, and the cost guide shows what each type costs over 10 years.

Questions people ask

How often should I test my well water?

At least once a year for total coliform bacteria, nitrate, total dissolved solids and pH, according to the CDC and EPA. Test again right away after flooding, well repairs, or any change in taste, color or smell, and more often if someone in the home is pregnant, nursing, very young or elderly.

How much does a well water test cost?

A basic bacteria and nitrate panel runs about $60 to $70 at Penn State's lab, and Wisconsin's state lab charges $35 each for bacteria and nitrate. Broader packages run $85 to $450. PFAS adds $300 or more per sample.

Are home water test kits good enough?

For quick checks of hardness or pH between lab tests, yes. For safety decisions, no: CDC and EPA both tell well owners to use a state-certified laboratory, and no test strip can measure PFAS at the parts-per-trillion levels EPA regulates.

What does a positive coliform result mean?

Total coliform bacteria indicate a path for surface contamination into the well. A positive E. coli result means fecal contamination, and you should not drink the water untreated. Call your county or state health department; the usual next steps are finding the entry point, disinfecting the well and retesting.

Do I need to test a brand-new well?

Yes, before anyone drinks from it. Some states require it: North Carolina's rules, for example, call for coliform samples from every new private well after the disinfectant used during construction has been flushed out.