Well water in Madison County, Nebraska
In Madison County, 12% of 286 tested well samples exceeded the EPA limit for nitrate (10 mg/L), based on public data from Nebraska Groundwater Quality Clearinghouse and USGS Water Quality Portal.
286 individual samples from 208 wells, 1964 to 2024. Data refreshed September 9, 2026.
What individual samples found
Each row summarizes every public sample for that contaminant inside Madison County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| Nitrate 1977 to 2024 | 286 | 93% | 12% | 1.85 | 56 | 10 mg/L EPA limit |
Sampled fewer than 10 times, too few to summarize: Uranium (1), Fluoride (1), Chloride (4), Sodium (3), Iron (2), Manganese (1), Radon (1).
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What this means
The contaminants most often above their limit here are nitrate (12% of 286 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Madison County
Treatment that fits the local profile
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Chloride
- Point-of-use reverse osmosis; Distillation
- Manganese
- Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Get your Madison County 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 Madison County.
Common questions
How high is radon in well water in Madison County?
The median radon level across 1 public samples in Madison County was 320 pCi/L, with a high of 320 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Madison County?
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
- Nebraska Groundwater Quality Clearinghouse: 284 samples in Madison County. Groundwater quality results compiled by the Nebraska Department of Environment and Energy, University of Nebraska and Nebraska Department of Agriculture in the Groundwater Quality Clearinghouse, contributed by Natural Resources Districts and state agencies. Retrieved September 9, 2026.
- USGS Water Quality Portal: 15 samples in Madison County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 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.