Water Tests for Wells: What to Test and When

Water tests for wells fall into two groups: the annual safety screen for bacteria and nitrate, and the periodic chemistry panel that guides treatment. A basic lab panel costs $40 - $150 and covers both if you order the right tests. Sampling technique decides whether the result means anything.

The Annual Safety Screen

Bacteria and nitrate are the two tests that should run every year. Both can change without any noticeable taste or odor, and both are common in agricultural and suburban areas.

The bacteria test looks for total coliform and E. coli. Coliforms are a broad group that includes soil and fecal organisms. A positive total coliform result means surface water or soil may be reaching the well, which points to a casing, cap, or grout problem. E. coli is the more specific indicator and calls for immediate action.

Nitrate is measured in milligrams per liter, and the federal drinking water limit is 10 mg/L. Nitrate comes from fertilizer, septic systems, and animal waste. It moves easily through soil and does not filter out with a standard cartridge. Boiling does not remove it; it concentrates it.

A lab panel that covers both usually runs $40 - $80. The sample must be collected in the lab’s sterile bottle and returned within the holding time, often 24 - 48 hours.

The Chemistry Panel for Treatment

Hardness, iron, manganese, pH, and alkalinity are not safety tests. They are the numbers that decide what equipment to buy.

Hardness tells you whether a softener is justified. The bands are 0 - 3 GPG soft, 3 - 7 moderately hard, 7 - 10 hard, and 10+ very hard. A softener installed runs $1,200 - $4,500.

Iron matters because softener resin tolerates only about 2 - 3 PPM before fouling accelerates. Above that, an iron filter at $800 - $2,500 installed belongs ahead of the softener. Manganese behaves similarly and stains fixtures black.

pH below 6.5 is corrosive to plumbing and calls for a neutralizer. Alkalinity buffers pH and affects how treatment behaves. None of these are health judgments; they are plumbing and equipment facts.

Metals and Emerging Contaminants

Arsenic, lead, uranium, and PFAS do not belong in an annual screen, but they belong in the first full panel and in periodic retests.

Arsenic occurs naturally in some aquifers and has no taste or smell. Lead usually comes from plumbing or a pump component rather than the aquifer, which is why sampling matters. Uranium appears in certain geologic regions. PFAS is a newer concern and needs a specialized lab method, which costs more.

A full suite at the top of these ranges runs $300 - $400. Most households do not need every test every year. Start with the basic panel, add metals if the area is known for them, and retest on a schedule.

Taking a Sample That Holds Up

1. Get the bottle from the lab first. A rinsed jar from the kitchen will contaminate the sample.
2. Bypass any softener, carbon filter, or RO unit, because treated water tells you nothing about the well.
3. Run the tap for five minutes to clear water sitting in the plumbing.
4. Fill the bottle to the line without touching the inside of the cap or the bottle mouth.
5. Chill the sample if the lab requires it and deliver it within the holding time.
6. Record the date, tap location, and whether treatment was bypassed.

For a bacteria sample, some labs ask for the aerator removed and a flame-sterilized tap. Follow the lab’s instructions exactly. A careless sample produces a false positive that costs a service call, or a false negative that hides a real problem.

Reading the Report Without Panicking

Lab reports list results against a limit or a range. Read three things: the result, the unit, and the comparison value.

Nitrate at 4 mg/L against a 10 mg/L limit is a pass with room. Nitrate at 12 mg/L is over the limit and points to a treatment decision, usually reverse osmosis at the point of use or a dedicated nitrate-selective system.

Iron at 0.4 PPM is cosmetic. Iron at 6 PPM is a treatment problem that a softener alone will not solve. Hardness at 18 GPG is very hard and justifies softening. pH at 6.2 is corrosive and needs a neutralizer before the water runs through new copper.

Do not treat a single high result as a permanent verdict. Resample to confirm, especially for bacteria, where a bad sample is common. Then treat the confirmed number.

What to Do With the Results

If the well passes the safety tests and the chemistry is mild, do nothing beyond retesting next year. If hardness is high, price a softener. If iron or manganese reads high, price an iron filter first. If nitrate or arsenic is over the limit, price point-of-use RO and consider a whole-house answer for the specific contaminant.

Keep every report in one folder, paper or digital. A treatment dealer will ask for the last one, and a buyer will ask for it at sale. A ten-year history of results is more useful than a single snapshot, because it shows whether anything is moving.

For the treatment side, see how to read a water test report, water testing cost, and best water test kit. If the well is new, drilling a water well covers the completion sequence and the first sample.