Well Water Testing Procedure

A practical sequence for testing private well water for drinking: what to measure first, how to take a sample, and what results do and do not mean.

Direct answer

Use a certified drinking-water lab. The first panel is usually total coliform and E. coli, plus nitrate if infants or nearby farming are involved. Follow the lab’s bottle and timing rules. A home strip test is not a substitute for a bacteria culture. Repeat at least yearly, and after floods, well repairs, or a change in taste or illness in the house.

What to test for drinking use

Bacteria: total coliform and E. coli — the priority for “is this well safe to drink?”
Nitrate: important where fertilizer or septic systems sit near the well, and for infants.
Basic chemistry: pH, hardness, iron, manganese — explain stains and taste, not always health.
Local extras: arsenic, fluoride, lead (from pipes), or other mapped groundwater risks.

Related overview: well water testing basics. A pocket TDS meter does not detect bacteria or fluoride. See what TDS measures.

Sampling procedure (typical lab kit)

Get the lab’s sterile bottle. Do not rinse it or touch the inside of the cap.
Choose a tap used for drinking, preferably before a home filter if you want the well itself.
Remove the aerator if the lab asks. Let cold water run 2–5 minutes.
Fill only as instructed. Leave headspace if the bottle mark says so.
Keep the sample cool and deliver within the lab’s time window (often the same day for bacteria).

A contaminated cap or a sample left warm overnight can produce a false bacteria result.

How to read the report

Coliform “present” means the well or plumbing may be influenced by surface or fecal contamination — treat it as a reason to stop drinking untreated water until you retest and fix the wellhead or plumbing. Chemical numbers should be compared with your national or state drinking-water limits, not with “TDS looks fine.” Guide: how to read a water quality report.

When to test again

Every year for bacteria, as a baseline habit
After flooding, a cracked casing, new pump work, or a nearby septic failure
If colour, smell, or household stomach illness changes suddenly

This page is the procedure. The shorter overview stays at Well Water Testing Basics.

Educational guide. Labs, limits, and well construction rules differ by country and state. Use a certified lab and local public-health advice for your well. About.