Crawford County, Kansas: Private Well Water Quality
USGS models estimate the private-well arsenic exposure across Crawford County, and USGS laboratory samples from at least 11 wells in the county show measured nitrate, manganese, iron and pH. The arsenic figure is an area estimate; the measurements are of other wells — neither is a test of your own well.
This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.
~0
people estimated to rely on private wells with modeled arsenic above the 10 µg/L EPA limit
0–0
90% confidence range for that estimate
18% of wells
sampled by USGS in the county measured > 300 µg/L for iron (11 wells)
Find out what's actually in your well
Private wells are not regulated by the EPA — nobody tests wells in Crawford County for you. Arsenic, nitrate and coliform bacteria are the three most common private-well problems, and none of them has a taste or smell. A certified lab test checks all of them at once; the CDC and EPA recommend testing every well at least once a year.
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Measured well tests in Crawford County
Unlike the arsenic estimate above, these are real laboratory results: the USGS has published chemistry from at least 11 wells in Crawford County, sampled 1988–2007. They describe other wells in the county — domestic, public-supply and monitoring wells — not your well.
| Parameter | Median | Wells over threshold | What the threshold means |
|---|---|---|---|
| Nitrate (as N)10 wells | 0 mg/L90th pct: 0 mg/L | 0%Low | > 10 mg/L (EPA MCL). Federal drinking-water limit. Nitrate from fertilizer, manure and septic systems; unsafe for infants and in pregnancy. |
| Manganese | Not enough USGS well samples in Crawford County (fewer than 5) — see the state page. | ||
| Iron11 wells | 31 µg/L90th pct: 510 µg/L | 18%Some | > 300 µg/L (EPA secondary standard). Aesthetic standard — rust-colored staining, metallic taste, clogged fixtures. Not a health limit. |
| pH | Not enough USGS well samples in Crawford County (fewer than 5) — see the state page. | ||
What the samples show
- Nitrate (as N): Nitrate was low in nearly all sampled wells (median 0 mg/L; 0% over the limit).
- Manganese: Not enough USGS well samples in Crawford County — see the state page.
- Iron: Iron affects some wells: 18% of sampled wells were over the 300 µg/L staining standard.
- pH: Not enough USGS well samples in Crawford County — see the state page.
What to do about the biggest finding (iron): Test for iron; an oxidizing iron filter or a softener stops the staining, and reverse osmosis polishes the drinking-water tap.
Source: USGS well samples aggregated to Crawford County, Kansas — manganese, pH and arsenic from USGS ScienceBase 5f36baa782cee144fb3873e8 (site medians, 1988–2019); nitrate and iron from McMahon et al. (2019), Environ. Sci. Technol. 53:29–38 (NWIS wells). County assignment by Census 2020 boundaries. Statistics shown only where ≥ 5 wells were sampled. USGS well samples; not a test of your well.
What the arsenic estimate means
Arsenic occurs naturally in bedrock and can dissolve into groundwater, so it shows up in private wells with no color, taste or smell. The USGS estimate above combines a statistical model of arsenic probability with the number of people on domestic wells in Crawford County. A higher number means more of your neighbors are likely drinking water over the federal limit — but your own well could be higher or lower. Long-term arsenic exposure is linked to skin, bladder and lung cancers, so the EPA sets the limit at 10 µg/L.
Statewide, Kansas also has a modeled nitrate exceedance of 5.2% of private-well residents — worth testing for at the same time.
What to do
- Test your well for arsenic, nitrate, manganese and iron — it's the only way to know your actual level.
- If arsenic or nitrate is present, install a reverse-osmosis system — carbon pitchers do not remove either.
- For manganese or iron staining, a whole-house oxidizing filter or softener is the fix; RO for the drinking tap.
- Re-test annually; well chemistry changes over time.
Iron: stop the staining at the source
Iron over 300 µg/L means rust stains and metallic taste house-wide. A whole-house iron filter or softener handles it; reverse osmosis polishes the drinking-water tap.
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