Guide · Updated October 12, 2026
Well water test kits
Direct answer
A hardware-store strip is a same-day screen for iron, hardness, or pH — not your annual bacteria or nitrate record. CDC’s private-well floor is total coliform, nitrates, TDS, and pH at a state-certified lab. If coliform or nitrate fails, take the sheet to the local health department.
| What to test | Why | EPA MCL / SMCL or guidance |
|---|---|---|
| Total coliform | CDC’s annual floor for a private well. A present result is a pathway warning, not a shopping trip. | Present/absent — any detected coliform is a positive until a clean retest CDC well-testing guidelines |
| E. coli | CDC: a positive fecal-coliform or E. coli result likely means feces got into the well. After a flood, this is the first health-department line. | Present/absent — any detected E. coli is a same-day health-department call CDC well-testing guidelines |
| Nitrate as N | Same yearly panel as coliform. A result at or above the public-system line goes to the health department. | 10 mg/L as N (EPA public-system MCL) EPA National Primary Drinking Water Regulations |
| pH | CDC annual floor. Low pH is a corrosion clue, not an iron-filter job. | 6.5–8.5 SMCL (aesthetic guideline) EPA secondary standards |
A test kit is a screening tool. A certified laboratory report is a decision document. They are not interchangeable.
EPA’s private-well pages and CDC’s well-testing guidance say to test every year for total coliform bacteria, nitrates, total dissolved solids, and pH. Those four items are not what most $20 strip cards measure well.
What a kit is for
Use a kit when you need a same-day clue before you spend money on the wrong tank: iron and hardness pads, pH paper, a field H2S check, a TDS meter. USGS Circular 1332 is the backdrop — aesthetic iron and hardness are common in domestic wells.
What a kit cannot do
Do not use a store kit as your annual bacteria or nitrate record. Coliform and E. coli need a sterile bottle, a hold time, and a state-certified laboratory — see Coliform Bacteria in Well Water. Nitrate is a health-based primary standard (10 mg/L as N). State pages already on this site: Nitrates in Iowa well water, Nitrates in Minnesota Well Water, Nitrates in Texas Well Water, and Nitrates in Wisconsin Well Water. If either line fails, contact the health department. This site is not medical advice.
State inventories now on this site: Pennsylvania, Florida, and Maine, and Iowa, and Minnesota, and Texas, and Wisconsin, and Michigan, and North Carolina, and New York. The official-search hub is certified labs by state.
What to do with the result
Units, MCL versus SMCL, and “ND” live on how to read a well water lab report. If floodwater reached the wellhead, a strip is not a clearance — start with Well flooded? What to test and when. A present coliform after a clean sample is still a health-department call, not a shopping trip. PFAS is not a strip card either — that panel belongs at a certified lab. See PFAS in private well water.
Mail-in certified-lab kits
A mail-in box from a certified laboratory is still a kit until the method and the analytes are on the report. Tap Score / SimpleLab is a class example of that mail-in path — not a ranked #1 pick. Confirm each analyte against a state-certified lab. Bacteria or nitrate still goes to the health department. Tracked URL and program status: disclosure.
Sources
- U.S. EPA, Private Wells. Protect Your Home’s Water.
- CDC. Guidelines for Testing Well Water.
- U.S. Geological Survey. Circular 1332.