Lab news · WI · Updated September 25, 2026
Wisconsin well-lab news
Direct answer
Dated notes from agency pages for wisconsin 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, Wisconsin DNR, DATCP, WSLH, and DHS. Not headlines. Public-system MCLs do not bind a private well.
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.
25 September 2026
WisconsinDNR’s “Test your private well water annually” page still publishes the owner-testing cadence: bacteria once a year and when taste, color, or smell changes; nitrate once a year and before the well will be used by someone who is or may become pregnant; arsenic every five years for most wells, and every year in Outagamie, Winnebago, or Brown counties or if a prior sample found arsenic. The same page says bacteria samples must reach the lab within 48 hours.
That is DNR’s published private-well cadence, not a statewide mandate at sale and not a medical diagnosis on this site. Use a certified lab. If coliform or nitrate fails, take the sheet to the local health department.
25 September 2026
WisconsinDNR’s certified-lab lists page still splits chemistry from bacteria. Chemistry files on the page when this note was written were labeled Accredited Laboratories — January 2026 (NR 809 / NR 812 drinking-water Excel downloads) and Approved Laboratories — April 2026 (radiochemistry and asbestos). Total coliform / E. coli remains a DATCP BactiLab directory. DNR defines registered labs as those that test only for themselves — they do not perform drinking-water testing.
Open the drinking-water chemistry Excel for nitrate, arsenic, and metals. Open BactiLab for bacteria. A wastewater or registered listing is not a private-well drinking-water certificate.
1 July 2026
WisconsinThe Wisconsin State Laboratory of Hygiene posted a public environmental and water testing price list effective July 1, 2026. Published homeowner examples: Homeowner Package $450 / 21 business days; HUD/FHA-VA loan package $146 / 7 business days (rush $292 / 2 days); standalone bacteria $35; nitrate $35; arsenic $38. Kits ship outbound free; the owner pays return shipping; WSLH bills after testing.
Those are WSLH’s published class examples, not a ranking and not a medical panel. Confirm the current list before you order. Bacteria or nitrate still goes to the health department.
Contaminant and parent pages
- Certified labs by state
- Orange stains
- Rotten-egg smell
- Iron filter vs. water softener
- How to read a well water lab report
- Coliform Bacteria in Well Water
- Blue-green corrosion and low pH
- Iron in Wisconsin Well Water
- Manganese in Wisconsin Well Water
- Hydrogen Sulfide in Wisconsin Well Water
- Hardness in Wisconsin Well Water
- Arsenic in Wisconsin Well Water
- Nitrates in Wisconsin Well Water
- Lead in Wisconsin Well Water
- Radon in Wisconsin Well Water
Related
See also the Wisconsin lab inventory, certified labs by state, and the homepage.