Well water in Fairfield, Wisconsin
In Fairfield, 9% of 87 private wells tested between 1989 and 2025 had nitrate above the Wisconsin enforcement standard (10 mg/L), according to the UWSP Well Water Quality Viewer.
87 private wells tested 2014 to 2023 in state summaries. Data refreshed September 9, 2026.
What homeowner tests found
Wisconsin Well Water Quality Viewer samples: private wells tested and reported to the state, 2014 to 2023. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA.
| Contaminant | Wells tested | Above state level | Median | 95th pct | Highest | State level | |
|---|---|---|---|---|---|---|---|
| Total coliform | 20 | 10% | |||||
| Nitrate | 87 | 9% | 4.26 | 13 | 15.3 | 10 mg/L | |
| Chloride | 29 | 0% | 11.7 | 49.8 | 65.5 | 250 mg/L | |
| Arsenic | 17 | 0% | 0 | 7 | 7 | 10 ug/L | |
| Copper | 13 | 0% | 0.016 | 0.798 | 0.798 | 1.3 mg/L | |
| Manganese | 13 | 0% | 0 | 24 | 24 | 300 ug/L | |
| Lead | 13 | 0% | 0 | 2 | 2 | 15 ug/L | |
| Sodium | 11 | 0% | 3.63 | 10 | 10 | 20 mg/L | |
| Iron | 10 | 0% | 0 | 116 | 116 | 300 ug/L | |
| E. coli | 2 | 0% |
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What this means
Among homeowners in Fairfield who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (10% of 20 wells) and nitrate (9% of 87 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.
What to test for in Fairfield
- Total coliform10% of 20 local wells tested were above the Wisconsin limit (any detection).
- Nitrate9% of 87 local wells tested were above the Wisconsin enforcement standard.
- Coliform bacteriaRecommended for every private well, every year.
Treatment that fits the local profile
- Total coliform
- Inspect and repair the well cap and casing, then shock chlorinate and retest; UV disinfection whole-house; Chlorination system
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
Get your Fairfield water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves Fairfield.
Common questions
How often should I test a private well in Fairfield?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Sources
- Wisconsin Well Water Quality Viewer samples: summaries for 10 contaminants in Fairfield, up to 87 wells each. Private well samples compiled by the UWSP Center for Watershed Science and Education from the DNR Groundwater Retrieval Network, DATCP surveys, the UWSP Water and Environmental Analysis Lab and county health programs, published in the Wisconsin Well Water Quality Viewer with Wisconsin DHS. Samples are located to the town, village or city they fall in; one result per well and parameter (the latest) so repeat samples do not double count; wells without a state well number are keyed by location. Shares are against Wisconsin NR 140 enforcement standards (arsenic 10 ug/L, nitrate 10 mg/L as N, manganese 300 ug/L, lead 15 ug/L, copper 1.3 mg/L) and the iron and chloride secondary levels. Many samples were submitted by homeowners with a reason to test, so shares can run above a random survey. Retrieved September 9, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.