Well pumps · how-to
Well water testing: what to test and how often
On city water, the utility tests for you. On a private well, nobody does — testing is the owner’s job. A good test plan tells you whether the water is safe to drink, what treatment (if any) you actually need, and whether something has changed at the well. Here is what to test, how often, and how to get results you can act on.
Bottom line
The CDC and EPA recommend testing a private well at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH.
Test more broadly when you buy a home, before choosing treatment, and any time the water changes or the well is flooded or repaired.
Your county or state health department or a state-certified lab is the best first stop; a mail-in kit such as the Safe Home Premium (50 parameters) or Safe Home Ultimate (200 parameters) is a practical alternative when local options are limited.
The yearly basics
| Test | Why it matters |
|---|---|
| Total coliform bacteria (and E. coli if coliform is present) | Shows whether surface water or contamination is reaching the well. A positive result means stop drinking untreated water until it is resolved. |
| Nitrate / nitrite | Comes from fertilizer, septic systems, and animal waste. Especially important for homes with infants or a pregnancy. |
| Total dissolved solids (TDS) | A broad indicator — a sudden change is a sign something is different at the well. |
| pH | Low pH water can corrode plumbing and pick up metals; it also affects which treatment works. |
Test these at least once, then as needed
- Hardness, iron, and manganese — the numbers you need to size a softener or iron filter. See sizing a softener by GPG and iron in well water.
- Arsenic, uranium, and radon — naturally occurring in some regions. Your health department can tell you whether they are common locally. See arsenic treatment if you get a high result.
- Lead and copper — usually from household plumbing rather than the aquifer; test at the tap.
- Hydrogen sulfide and sulfate — if you notice a rotten-egg smell. See rotten-egg smell and iron bacteria.
- Pesticides, VOCs, or PFAS — if the well is near farm fields, fuel storage, landfills, or industrial sites, or if your health department flags them.
Test right away when…
- The well has been flooded, or surface water pooled around the wellhead.
- The well, pump, or pressure tank has been worked on (a new pump, a pulled drop pipe, a new tank).
- Taste, smell, color, or cloudiness changes.
- Someone in the house gets a stomach illness that could be water-related.
- You are buying or selling a home with a well, or a baby is on the way.
- A neighbor reports a problem, or there is a spill or new land use nearby.
Lab vs DIY kits
| Option | Best for | Limits |
|---|---|---|
| State-certified local lab (often via the county health department) | Safety decisions, real-estate transactions, and anything you will base treatment on | You may need to pick up bottles and deliver the sample within a holding time |
| Mail-in lab kit — Safe Home Premium / Safe Home Ultimate | A broad baseline when you do not have a convenient local lab; lab fees and return shipping are included per the listings | Premium covers metals, inorganics, and physical properties; Ultimate adds organics, pesticides, and disinfection byproducts. Each includes a DIY coliform test rather than a lab bacteria test. |
| DIY bacteria test — Safe Home DIY Bacteria test, 2-pack | Checking for coliform between lab tests, or after shock chlorination | Presence/absence screening only; confirm a positive with a certified lab |
| Test strips and hardness kits — well water test strips / Hach 5-B hardness kit | Quick checks of hardness, pH, and iron when tuning treatment equipment | Screening only; not a substitute for a lab test for health contaminants |
How to take a good sample
- Follow the lab’s instructions exactly — bottle type, how long to run the water, and how fast to ship are part of the test.
- Sample before any treatment (softener, filter, UV) when you want to know what the well itself produces. Use a tap that bypasses treatment, or put equipment in bypass. Sample after treatment separately if you want to know whether it is working.
- Remove aerators and avoid swivel or leaky faucets for bacteria samples.
- Do not touch the inside of the bottle or cap, and keep the sample cool if the lab says to.
- Write down the date, the tap used, and anything unusual — it makes year-to-year comparison possible.
After the results
- Positive coliform or E. coli: use bottled or boiled water as your health department advises, inspect the well cap and casing, and ask a licensed well contractor about disinfection and repairs.
- Nitrate, arsenic, or other health contaminants above the EPA limit: talk with your health department and a water-treatment professional before buying equipment — the right treatment depends on the full result.
- Hardness, iron, or pH issues: these are usually treatment and comfort problems. Use the numbers to size equipment rather than guessing.
- Keep every report. A change from last year is often more useful than a single number.
When to call a pro
- Any positive bacteria result, or a health contaminant above the EPA limit.
- Results change sharply from one year to the next.
- Sand, cloudiness, or air in the water along with a change in test results — that can point to a well or pump problem rather than water quality alone.
- The wellhead is damaged, below grade, or missing a sanitary cap.
Getting help
For sampling, interpreting results, and treatment, start with your county or state health department, a state-certified lab, and a licensed well contractor or water-treatment professional. If testing turns up a pump problem, R.E. Merrill & Associates is a Grundfos dealer — we can talk through SQ and SQE options with you and your contractor. Contact R.E. Merrill & Associates.
Related across the site
- Best water hardness test kits — strips vs titration vs digital
- How to clean a brine tank — upkeep for softeners on well water
- Sump pump check valves — keep basement water away from the wellhead and foundation
Sources
- CDC, private well water testing guidance — test at least once a year for total coliform bacteria, nitrates, total dissolved solids, and pH; test more often after changes or problems.
- U.S. EPA, private drinking water wells — owners are responsible for testing; use a state-certified laboratory.
- Safe Home Premium (SH-PWT1) and Ultimate (SH-UWT1) Amazon listings — 50 and 200 parameters tested at the company’s EPA-certified lab; lab fees and return shipping included; DIY coliform test included.
- Safe Home DIY Bacteria in Water Test Kit Amazon listing — presence/absence screening for coliform bacteria including E. coli.