Well Water Testing: What to Test, How Often and Cost
Last updated: November 6, 2026 · Sources: EPA, USGS, Extension Foundation, Angi
If you have a private well, you are responsible for testing it. Test your well water at least once a year for total coliform bacteria and nitrate, plus pH and total dissolved solids. Test at least once for arsenic, uranium and lead, and test again right away after flooding, repairs or any change in taste, color or smell. Use a state-certified lab for health-related tests.
About 43 million Americans, roughly 15% of the population, get their drinking water from private wells, according to the USGS. Unlike city water, private wells are not regulated by the EPA, so nobody else checks them. This guide explains what to test for, how often, how to take a sample, what it costs and what to do with the results.
Well water testing at a glance
- Every year: total coliform bacteria, nitrate, pH, total dissolved solids
- At least once: arsenic, uranium, lead, hardness, fluoride
- Right away: after floods, repairs or changes in taste, color or smell
- Where: a state-certified drinking water laboratory
- Cost: about $100 to $350 for advanced lab testing (Angi)
Already have results? Enter them in our free water test results checker to compare them with EPA limits.
Why Well Water Testing Matters
Public water systems must test their water and report the results, but in most states private well owners are not required to test at all. Problems like bacteria, nitrate and arsenic usually have no taste or smell, so you cannot tell if your water is safe by looking at it.
When the USGS sampled about 2,100 private wells across the country, roughly one in five had at least one contaminant at a level that could be a health concern. Most were natural, like arsenic, radon and uranium, but nitrate from fertilizer and septic systems was also common.
What to Test Your Well Water For
| Test | Why it matters | How often |
|---|---|---|
| Total coliform bacteria | Signals that germs may be getting into the well | Every year |
| Nitrate | Dangerous for infants; comes from fertilizer, manure and septic systems | Every year (especially near farms) |
| pH and TDS | Show corrosive water and overall mineral content | Every year |
| Arsenic and uranium | Natural in many regions; long-term health risks | At least once |
| Lead | Can leach from old plumbing and brass fittings | Once, if plumbing is older |
| Hardness, iron, manganese | Cause scale, stains and bad taste | Once, then every few years |
| VOCs and pesticides | Risk near fuel tanks, landfills or farm fields | Every 5 to 10 years if at risk |
| PFAS | Risk near airports, military bases or factories | If you live near a known source |
Your county health department can tell you about problems that are common in your area, such as arsenic in parts of New England and the West, or uranium in some granite regions.
How Often to Test Well Water
The EPA recommends testing private wells at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH. Test more often, or right away, if:
- Your area floods or the well is damaged
- You repair or replace the well, pump or pipes
- The water changes in taste, color or smell
- Someone in the home is pregnant or you have an infant
- Family members have repeated stomach problems
How to Test Well Water
- Contact a certified lab. Your state health or environmental department keeps a list of certified drinking water laboratories. Many county health departments offer testing too.
- Get the right bottles. The lab will send sterile sample bottles and instructions. Bacteria samples have strict rules.
- Take the sample correctly. Use a cold-water tap without an aerator or filter, run the water first, and do not touch the inside of the bottle or cap.
- Ship it fast. Bacteria samples usually must reach the lab within about a day, so collect early in the week.
- Read the results against the standards. Compare each result with EPA drinking water standards; the lab or health department can help.
Home test kits vs. certified labs
Home kits and test strips are cheap and fast for screening things like hardness, pH and iron. See our guide on how to test water hardness. For health-related contaminants like bacteria, nitrate, arsenic, lead and PFAS, use a certified lab.
How Much Does Well Water Testing Cost?
| Option | Typical cost |
|---|---|
| State or county lab basic test (bacteria, nitrate) | Often low cost; varies by state |
| Advanced lab water testing | $100 to $350 |
| Well inspection | About $375 on average |
| Comprehensive well inspection with water testing | $700 to $750 |
Cost ranges from Angi (2025 data). Some states offer free or discounted tests for new wells or families with infants.
What to Do With Your Results
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- Bacteria found: stop drinking the water, use bottled water, contact your health department, inspect the well cap and casing, and shock chlorinate the well before retesting.
- High nitrate: do not give the water to infants; consider reverse osmosis and look for sources like septic systems or fertilizer.
- Arsenic, uranium or lead: choose treatment certified for that contaminant, usually reverse osmosis for drinking water.
- Iron: see how to remove iron from well water.
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- Hard water, iron or sulfur smell: these are mostly nuisance problems, fixed with a water softener or whole house filter.
Always retest after installing treatment to make sure it works.
Frequently Asked Questions
How often should well water be tested?
Test a private well at least once a year for total coliform bacteria and nitrate, and test pH and total dissolved solids as well. Test right away after flooding, well repairs or any change in taste, color or smell, and test once for arsenic, uranium and lead.
How much does a well water test cost?
A basic bacteria and nitrate test from a state or county lab is often low cost. Angi puts advanced lab water testing at about $100 to $350, and a comprehensive well inspection with water testing at about $700 to $750.
Who tests well water near me?
Start with your county or state health department, which often runs or recommends certified labs. You can also search your state’s list of certified drinking water laboratories, or ask a licensed well contractor.
Are home well water test kits accurate?
Home kits are useful for quick screening of things like hardness, pH or iron. For bacteria, nitrate, arsenic, lead and PFAS, use a state-certified laboratory, because results need to be accurate enough to make health decisions.
What should I do if my well water test is bad?
Do not drink the water if bacteria or nitrate are above safe levels; use bottled water and contact your health department. Find and fix the cause, such as a damaged well cap, then choose treatment for the specific problem and retest.
The Bottom Line
Well water testing is the only way to know your private well is safe. Test every year for bacteria, nitrate, pH and TDS, test once for arsenic, uranium and lead, and test right away after floods, repairs or any change in your water. Use a state-certified lab, then treat the specific problems your results show.
Sources: EPA: Private drinking water wells; USGS: Domestic (private) supply wells; Extension Foundation: Testing recommendations for private wells; Angi: Well inspection cost.
