Guide · Updated October 16, 2026
Certified labs by state
Direct answer
A private well is tested at a state-certified drinking-water lab, not at a store counter. This hub lists eleven Well Diagnosis inventories: Pennsylvania, Florida, Maine, Iowa, Minnesota, Texas, Wisconsin, Michigan, North Carolina, New York, and New Hampshire, plus the official state search for each. 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 |
| 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 |
| Total dissolved solids | CDC annual floor with coliform, nitrate, and pH. | 500 mg/L SMCL (aesthetic guideline) EPA secondary standards |
A private well is not a public water system. Use a state-certified laboratory. This site does not run a lab and does not certify anyone. The eleven live inventories are Pennsylvania, Florida, Maine, Iowa, Minnesota, Texas, Wisconsin, Michigan, and North Carolina, and New York, and New Hampshire.
CDC and EPA both say to use a state-certified laboratory for drinking-water tests. Certification is a state job. EPA publishes contacts for each state’s certification program. That page is the root of this directory.
Inventory pages tell you how to use the official search and list labs that publicly take private-well work. Inventories now include Pennsylvania (radon in groundwater is common in some Pennsylvania units — see Radon in Pennsylvania well water; lead at the tap is usually plumbing — see Lead in Pennsylvania Well Water) , Florida (limestone hardness is common in Florida wells — see Hard Water in Florida Wells; rotten-egg odor is hydrogen sulfide — see Hydrogen Sulfide in Florida Well Water) , Maine (arsenic is common in Maine wells — see Arsenic in Maine well water; uranium MEG and tip-sheet split — see Uranium in Maine well water) , and Iowa (nitrate is common in Iowa wells — see Nitrates in Iowa well water) , and Minnesota (rotten-egg odor is hydrogen sulfide — see Hydrogen Sulfide in Minnesota Well Water; iron stains fixtures and can look clear until it rusts — see Iron in Minnesota Well Water; nitrate is a yearly MDH test — see Nitrates in Minnesota Well Water; MDH’s published private-well cadence puts manganese on the same “at least once” list as arsenic and lead — see Manganese in Minnesota Well Water; arsenic is invisible in the glass — see Arsenic in Minnesota Well Water; hardness is calcium and magnesium — see Hardness in Minnesota Well Water; MDH’s five-contaminant cadence does not include PFAS — see PFAS in private well water) , and Texas (TCEQ NELAP-accredited labs; the state does not regulate private-well water quality — see Texas well-lab news; nitrate is invisible in the glass — see Nitrates in Texas Well Water; arsenic is invisible in the glass — see Arsenic in Texas Well Water) , and Wisconsin (DNR chemistry lists plus DATCP bacteria certification; owner-testing cadence on DNR’s annual private-well page — see Wisconsin well-lab news; nitrate is invisible in the glass — see Nitrates in Wisconsin Well Water; arsenic is invisible in the glass — see Arsenic in Wisconsin Well Water; hardness is calcium and magnesium — see Hardness in Wisconsin Well Water; iron stains fixtures and can look clear until it rusts — see Iron in Wisconsin Well Water; rotten-egg odor is hydrogen sulfide — see Hydrogen Sulfide in Wisconsin Well Water; manganese can stain black-brown — see Manganese in Wisconsin Well Water; lead is usually a plumbing number — see Lead in Wisconsin Well Water; radon-in-water is a pCi/L sheet, not indoor-air 4 — see Radon in Wisconsin Well Water) , and Michigan (EGLE-certified drinking-water lists plus the EGLE Drinking Water Laboratory kit path; EGLE yearly coliform and nitrates, MDHHS arsenic and lead every 3–5 years, PFAS at least once as MDHHS guidance — see Michigan well-lab news and PFAS in private well water) , and North Carolina (NCDHHS / SLPH new-well 30-day bacteria-plus-inorganic panel plus the certified-lab search; existing wells: coliform yearly; PFAS is not on that new-well panel — see North Carolina well-lab news and PFAS in private well water) , and New York (NYS DOH ELAP potable-water search plus county health department kits; yearly bacteria and a 3 to 5 year extra-contaminant cadence; limited free PFAS testing in six named counties when the pilot is open — see New York well-lab news and PFAS in private well water) , and New Hampshire (NHELAP accredited-lab search plus the NH Public Health Laboratories fee-for-service homeowner path; NHDES yearly bacteria, nitrate, and nitrite, and the rest of the recommended panel every 3 to 5 years; limited NHDES PFAS sampling when a request is selected. See New Hampshire well-lab news and PFAS in private well water) . If bacteria or nitrate fails, the next reader of the report is the health department, not a filter brand. The bacteria reading order is Coliform Bacteria in Well Water. If floodwater reached the wellhead, start with Well flooded? What to test and when— other water, electricity, disinfection, then a certified bacteria test. No product list on that page.
From a stain to a certified lab
Match the fixture first, then come back here for the official search. Orange on porcelain is usually iron — see Orange stains in well water. A boiled-egg smell is hydrogen sulfide — see Rotten-egg smell in well water. Jelly in the toilet tank is biofilm — see Slimy toilet tank on a private well. Blue-green on porcelain is copper leaving the pipe — see Blue-green corrosion and low pH. Each of those pages points at the contaminant × state guides and the Michigan and North Carolina inventories the same way it points at Pennsylvania through Wisconsin.
What to test every year
CDC’s published private-well floor is total coliform, nitrates, total dissolved solids, and pH. EPA’s private-well pages say the same pair — bacteria and nitrate — is the minimum. That panel does not change because the well is in Michigan or North Carolina. A present coliform or a nitrate at or above 10 mg/L as N is a local-health-department call, not a filter quote. PFAS is a certified-lab add-on, not that yearly floor — see PFAS in private well water.
State pages on this site
What “certified” means
States accredit environmental laboratories for fields of accreditation: a matrix (drinking water), a method, and an analyte. A lab can be excellent at wastewater metals and useless for drinking-water coliform. Ask for the analyte.
NELAP is a national standard some states use. State-only accreditation can be just as real. What you want is current drinking-water accreditation for the tests on your order form.
How not to use a directory
- Do not treat a listing as a current certificate. Accreditation lapses.
- Do not pick the cheapest coliform and assume metals are included.
- Do not send a treatment salesperson’s unlabeled printout as your annual test.
- Do not ignore a present coliform because an iron number looks fine.
A mail-in kit is not a substitute for the official search. Tap Score / SimpleLab is an approved class example of a mail-in certified-lab kit — not a ranked pick. Confirm each analyte on a current certificate. Bacteria or nitrate still goes to the health department. See the disclosure.
This site is not medical, legal, or engineering advice. Bacteria or nitrate results belong with your health department.