What does my well water test result mean?
Type in the results from your lab report, as many as it has, and check them all at once against federal limits and, if you pick your state, your state’s own values. Federal limits are written for public water systems, not private wells, but they are the usual yardstick. Nothing you type leaves your browser.
The limits this checker uses
Primary limits (MCLs) protect health and are enforced for public water systems. Secondary standards cover taste, color and staining and are not enforced. A health advisory is EPA guidance, not a rule. None of them is legally binding on a private well.
| Contaminant | Benchmark | Source |
|---|---|---|
| Nitrate | EPA limit (MCL): 10 mg/L | [1] [6] |
| Nitrite | EPA limit (MCL): 1 mg/L | [1] |
| Arsenic | EPA limit (MCL): 10 µg/L | [1] |
| Lead | Action level from Nov 1, 2027: 10 µg/L; Action level today: 15 µg/L | [1] |
| Copper | EPA secondary standard (taste, staining): 1 mg/L; EPA action level: 1.3 mg/L | [1] [2] |
| Uranium | EPA limit (MCL): 30 µg/L | [1] |
| Gross alpha | EPA limit (MCL): 15 pCi/L | [1] |
| Radium 226 + 228 (combined) | EPA limit (MCL): 5 pCi/L | [1] |
| Radon in water | Proposed limit (1999, never final): 300 pCi/L; Proposed alternative limit (never final): 4000 pCi/L | [5] |
| Manganese | EPA secondary standard (staining, taste): 50 µg/L; EPA lifetime health advisory: 0.3 mg/L | [2] [3] |
| PFOA (a PFAS) | EPA limit (MCL, 2024 rule): 4 ng/L | [4] [1] |
| PFOS (a PFAS) | EPA limit (MCL, 2024 rule): 4 ng/L | [4] [1] |
| Benzene | EPA limit (MCL): 5 µg/L | [1] |
| Trichloroethylene (TCE) | EPA limit (MCL): 5 µg/L | [1] |
| Tetrachloroethylene (PCE) | EPA limit (MCL): 5 µg/L | [1] |
| Vinyl chloride | EPA limit (MCL): 2 µg/L | [1] |
| Fluoride | EPA secondary standard (tooth discoloration): 2 mg/L; EPA limit (MCL): 4 mg/L | [1] [2] |
| Barium | EPA limit (MCL): 2 mg/L | [1] |
| Iron | EPA secondary standard (rusty color, staining): 0.3 mg/L | [2] |
| Total dissolved solids (TDS) | EPA secondary standard: 500 mg/L | [2] |
| Chloride | EPA secondary standard (salty taste): 250 mg/L | [2] |
| Sulfate | EPA secondary standard (salty taste): 250 mg/L | [2] |
| pH | EPA secondary range, low end: 6.5; EPA secondary range, high end: 8.5 | [2] |
| Total coliform bacteria | Any positive result (health goal: zero) | [1] |
| E. coli | Any positive result (health goal: zero) | [1] |
State values that differ from the federal ones
Some states set their own, lower values or apply health-based values to private wells. Each is listed in the state’s own words, with what it applies to; checked 14 Nov 2026.
| State | Contaminant | Value | Applies to | Source |
|---|---|---|---|---|
| California | Benzene | California MCL: 1 µg/L | public water systems | source |
| California | Fluoride | California MCL: 2 mg/L | public water systems | source |
| California | Vinyl chloride | California MCL: 0.5 µg/L | public water systems | source |
| Michigan | Lead | Michigan lead action level: 12 µg/L | community and nontransient noncommunity water supplies (90th percentile of tap samples) | source |
| Minnesota | Benzene | Minnesota Health Risk Limit (HRL): 2 µg/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| Minnesota | Manganese | Minnesota Health Risk Limit (HRL), short-term: 0.1 mg/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| Minnesota | Tetrachloroethylene (PCE) | Minnesota Health Risk Limit (HRL), cancer: 4 µg/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| Minnesota | PFOA (a PFAS) | Minnesota Health Risk Limit (HRL), cancer: 0.0079 ng/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| Minnesota | PFOS (a PFAS) | Minnesota Health Risk Limit (HRL): 2.3 ng/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| Minnesota | Trichloroethylene (TCE) | Minnesota Health Risk Limit (HRL): 0.4 µg/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| Minnesota | Vinyl chloride | Minnesota Health Risk Limit (HRL), cancer: 0.2 µg/L | groundwater that is used for drinking water (guidance; MDH: public water systems are not required to meet HBVs) | source |
| New Hampshire | Arsenic | New Hampshire MCL: 5 µg/L | public water systems | source |
| New Jersey | Arsenic | New Jersey MCL: 5 µg/L | public water systems (NJ Department of Health tells private well owners to act on results above federal and state public drinking water standards) | source |
| New Jersey | Benzene | New Jersey MCL: 1 µg/L | public water systems (NJ Department of Health tells private well owners to act on results above federal and state public drinking water standards) | source |
| New Jersey | Tetrachloroethylene (PCE) | New Jersey MCL: 1 µg/L | public water systems (NJ Department of Health tells private well owners to act on results above federal and state public drinking water standards) | source |
| New Jersey | PFOA (a PFAS) | New Jersey MCL: 14 ng/L | public water systems (NJ Department of Health tells private well owners to act on results above federal and state public drinking water standards) | source |
| New Jersey | PFOS (a PFAS) | New Jersey MCL: 13 ng/L | public water systems (NJ Department of Health tells private well owners to act on results above federal and state public drinking water standards) | source |
| New Jersey | Trichloroethylene (TCE) | New Jersey MCL: 1 µg/L | public water systems (NJ Department of Health tells private well owners to act on results above federal and state public drinking water standards) | source |
| New York | PFOA (a PFAS) | New York State MCL: 10 ng/L | public water systems | source |
| New York | PFOS (a PFAS) | New York State MCL: 10 ng/L | public water systems | source |
| Pennsylvania | PFOA (a PFAS) | Pennsylvania MCL: 14 ng/L | public water systems | source |
| Pennsylvania | PFOS (a PFAS) | Pennsylvania MCL: 18 ng/L | public water systems | source |
| Vermont | Tetrachloroethylene (PCE) | Vermont action level (VAL): 1 µg/L | private drinking water (wells and springs); Health Department guideline, not an enforceable standard | source |
| Vermont | Trichloroethylene (TCE) | Vermont action level (VAL): 0.5 µg/L | private drinking water (wells and springs); Health Department guideline, not an enforceable standard | source |
| Wisconsin | Lead | Wisconsin DHS action recommendation (laboratory detection level): 0.3 µg/L | drinking water, including private wells (DHS recommendation) | source |
| Wisconsin | Trichloroethylene (TCE) | Wisconsin DHS recommendation for private wells (take action at 0.5 µg/L or more; proposed groundwater standard not adopted): 0.5 µg/L | private well water | source |
Sources
- U.S. EPA, National Primary Drinking Water Regulations (last updated Aug 31, 2026)
- U.S. EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals (last updated May 26, 2026)
- U.S. EPA, Drinking Water Health Advisory for Manganese (EPA-822-R-04-003, January 2004)
- U.S. EPA, Per- and Polyfluoroalkyl Substances (PFAS) in drinking water (last updated May 18, 2026)
- U.S. EPA (archive), Radon in Drinking Water: proposed rule basic information
- University of Georgia AESL, Drinking Water Interpretation and Recommendations (nitrate-N x 4.43 = nitrate)
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