Chloride in Missouri well water
In Missouri, <1% of 10,678 private wells tested between 2010 and 2023 had chloride above the EPA secondary standard (250 mg/L), according to Missouri DHSS.
Chloride mainly comes from road salt and water softener discharge. Above 250 mg/L water tastes salty and corrodes plumbing. Rising chloride in a well usually means road salt is reaching the aquifer.
Check your chloride number
Type the value from your lab report. It is compared to the EPA secondary standard and the EPA limit, the same way the full interpretation does it.
Test your Missouri well for chloride
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove chloride
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For chloride
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for chloride in Missouri: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (250 mg/L) in tests homeowners sent to the state lab, 2010 to 2023.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Lewis | 116 | ||
| Pike | 38 | ||
| Henry | 62 | ||
| Ralls | 97 | ||
| Lincoln | 104 | ||
| St. Charles | 60 | ||
| Clark | 82 | ||
| Platte | 82 | ||
| Cooper | 234 | ||
| Livingston | 32 | ||
| Ste. Genevieve | 40 | ||
| Perry | 166 | ||
| Franklin | 45 | ||
| Callaway | 47 | ||
| Mississippi | 96 |
By county, from individual samples
Public monitoring samples against the EPA limit; counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Carroll | no limit | 50 | 100% | 95 | 8,250 mg/L |
| Jefferson | no limit | 166 | 100% | 5.5 | 5,050 mg/L |
| St. Charles | no limit | 331 | 100% | 4.7 | 6,900 mg/L |
| Holt | no limit | 31 | 100% | 47.1 | 24,600 mg/L |
| Scott | no limit | 48 | 100% | 13 | 310 mg/L |
| Callaway | no limit | 55 | 100% | 5.5 | 910 mg/L |
| Stoddard | no limit | 75 | 100% | 19 | 1,200 mg/L |
| New Madrid | no limit | 100 | 100% | 18 | 1,300 mg/L |
| Jackson | no limit | 551 | 100% | 23.7 | 17,600 mg/L |
| Saline | no limit | 68 | 100% | 19.9 | 8,990 mg/L |
| Cass | no limit | 40 | 100% | 1,010 | 19,000 mg/L |
| Chariton | no limit | 45 | 100% | 87 | 8,110 mg/L |
| Cape Girardeau | no limit | 63 | 100% | 7.3 | 370 mg/L |
| Dunklin | no limit | 64 | 100% | 44 | 110 mg/L |
| St. Louis | no limit | 199 | 100% | 14 | 10,000 mg/L |
- Chouteau township, Clay County100% detected of 106
- Como township, New Madrid County100% detected of 35
- Blue township, Jackson County100% detected of 452
- Piney township, Pulaski County100% detected of 248
- Joplin township, Jasper County100% detected of 31
- Boone township, St. Charles County100% detected of 240
- Cullen township, Pulaski County100% detected of 85
- Cape Girardeau township, Cape Girardeau County100% detected of 38
- Meramec township, St. Louis County100% detected of 40
- Carroll township, Reynolds County100% detected of 57
- Chariton township, Macon County100% detected of 31
- Narrows township, Macon County100% detected of 40
- New Haven township, Franklin County100% detected of 35
- Randolph township, St. Francois County100% detected of 35
- St. Francois township, St. Francois County99% detected of 68
- Roubidoux township, Pulaski County97% detected of 155
Sources
- Missouri DHSS private well sampling summaries: County summaries of private well samples analyzed by the Missouri State Public Health Laboratory, 2010 to 2023, published by the Missouri Department of Health and Senior Services. Counts are samples, not distinct wells. Shares are against the EPA maximum contaminant level, or the EPA secondary standard for chloride and iron. Counties with fewer than 20 samples are flagged unreliable by DHSS and are kept here with their counts so the threshold rule can judge them. Barium, sulfate and zinc layers exist but have no contaminant page yet. Retrieved September 15, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. chloride counts and shares are listed on each county and town page with their sources.