Lab news · ME · Updated August 31, 2026
Maine well-lab news
Direct answer
Dated notes from agency pages for maine well owners. Public-system MCLs do not bind a private well. Bacteria or nitrate on a lab sheet still goes to the 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 |
Dated notes from EPA, Maine CDC, and the 132nd Legislature. Not headlines. Maine’s 20 ng/L public-system PFAS sum is not a private-well MCL.
Dated notes from agency pages, not invented headlines. Public-system MCLs do not bind a private well unless the item is about a private-well statute. Bacteria or nitrate on a lab sheet still goes to the health department. This site is not medical advice.
18 May 2026
FederalEPA proposed keeping the PFOA and PFOS maximum contaminant levels at 4.0 ppt for public water systems, and letting requesting systems take until April 26, 2031 instead of April 26, 2029. The comment period closed July 20, 2026. EPA last updated that page July 23, 2026.
This is a proposal, not a final rule. It does not require a private-well owner to test or treat. Public-system MCLs do not bind a kitchen tap on a private well.
18 May 2026
FederalIn the same window, EPA separately proposed rescinding MCLs for PFHxS, PFNA, HFPO-DA (GenX), and the Hazard Index mixture. That page was live when this note was written and is linked from the extension-rule page.
That action is still a proposal. Do not read it as those limits being gone. A private-well owner is not under that public-system rule either way.
31 August 2026
MaineMaine CDC’s private-well page states that private wells are unregulated and that property owners are responsible for testing. CDC recommends annual coliform, E. coli, and nitrate-nitrite, and every 3–5 years arsenic plus the rest of the listed metals, radon, and uranium panel.
Schedule the annual bacteria and nitrate pair even if no one is selling a filter. Bacteria or nitrate on a sheet still goes to the health department.
16 April 2026
MaineLD 493 / HP 322 was enacted and signed April 16, 2026 as Public Law Chapter 746: An Act to Expand Testing for Perfluoroalkyl and Polyfluoroalkyl Substances to Private Drinking Water Wells. The chapter text requires a landlord of a residential building with a private-well water supply to test that well for PFAS no later than January 1, 2027, through a laboratory certified under 22 M.R.S. §567 using the most recent EPA methods that quantify the maximum amount of PFAS detected. It also amends the residential property-disclosure list so a seller must say whether a water test detected PFAS, and it adds PFAS to DHHS’s uniform private-well testing recommendation.
That landlord/disclosure statute is about private wells. It is not a statewide mandate that every owner-occupied well be tested by that date. Owner-occupants still choose when to add PFAS to a lab order.
Maine Legislature: LD 493 / Public Law Chapter 746 (printed chapter PDF)
June 2021
MaineMaine CDC’s PFAS and well-water page states that in June 2021 the Legislature set a State drinking-water standard of 20 ng/L in public water supplies for the combined sum of six PFAS (PFOA, PFOS, PFHpA, PFNA, PFDA, and PFHxS).
Private wells are not that public-system rule. Do not treat 20 ng/L as a kitchen-tap MCL unless a later private-well statute says so.
Contaminant and parent pages
Related
See also the Maine lab inventory, certified labs by state, and the homepage.