Low-cost state testing
Missouri's state lab tests well water for bacteria for a $10 fee. Check which tests it includes before you count on it for nitrate.
Missouri's private well pageNitrate in Missouri well water, by county
Nitrate is worth checking in 1 of the 10 Missouri counties with 10 or more tested wells, and rare in the rest. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.
How Missouri compares with the rest of the country
Across Missouri, under 1 in 50 tested wells had nitrate over the EPA limit of 10 mg/L (5 of 408). Across all tested wells in the US it's about 1 in 12. That's less often than in the country as a whole. Counties still differ, so check yours below.
Why it matters: It's dangerous for babies under 6 months, because it keeps their blood from carrying enough oxygen.
Nitrate soaks down into groundwater from fertilizer, manure and septic systems.
Nitrate in tested wells, county by county
Share of each county's tested wells with at least one result over the EPA limit of 10 mg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.
| County | Wells tested | Wells over the limit | Level |
|---|---|---|---|
| Barry County | 36 | Worth checking | |
| Boone County | 47 | Rare | |
| Pulaski County | 75 | Rare | |
| Jackson County | 62 | Rare | |
| St. Francois County | 27 | Rare | |
| Reynolds County | 26 | Rare | |
| Franklin County | 16 | Rare | |
| St. Charles County | 15 | Rare | |
| Clay County | 11 | Rare | |
| Newton County | 11 | Rare |
46 more Missouri counties have 1 to 9 tested wells for nitrate, too few to rate.
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Where to get your well tested for nitrate in Missouri
A lab Missouri certifies
Ask for nitrate by name. Results from a certified lab count for a home sale or a loan.
Labs certified by MissouriA mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include nitrate.
Compare kitsKeep reading about wells in Missouri
- Well water testing in Missouri: how to get tested and what turns up statewide
- Nitrate in well water: where it comes from, what it does and how to remove it
- Arsenic in Missouri wells, by county
- Manganese in Missouri wells, by county
- Lead in Missouri wells, by county
Questions people ask about nitrate in Missouri
Is there nitrate in Missouri well water?
Nitrate is worth checking in 1 of the 10 Missouri counties with 10 or more tested wells, and rare in the rest. Across Missouri, under 1 in 50 tested wells had nitrate over the EPA limit of 10 mg/L (5 of 408). Across all tested wells in the US it's about 1 in 12. That's less often than in the country as a whole. Counties still differ, so check yours below.
Where can I get my well tested for nitrate in Missouri?
Missouri's state lab tests well water for bacteria for a $10 fee. If that doesn't cover you, use a lab certified by Missouri for drinking water, or a mail-in kit that includes nitrate from a certified lab.
See Missouri's list of certified labs, or compare mail-in kits.
Where these numbers come from
- Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 10 mg/L. Wells tested for studies and monitoring, not a random sample of homes.
- Likely overstated: our own check of who tested the wells, when and where. How we check.
- State programs and links: Missouri Department of Health and Senior Services.