Well Water in Missouri
Contaminant risks, testing requirements, and treatment recommendations for private well owners in Missouri.
Missouri Geology and Groundwater
Missouri sits on Ozark Plateau karst and glacial drift. This geology directly determines what contaminants are likely in private well water. Moderate risk exists for radon, nitrate, PFAS.
Contaminant Risk Profile
| Contaminant | Risk Level | Why |
|---|---|---|
| Arsenic | Low risk | Generally low in this region's geology. |
| Nitrate | Moderate risk | Some areas near farmland or septic systems may have elevated levels. |
| Radon | Moderate risk | Some bedrock types in this state produce radon. |
| PFAS | Moderate risk | Some known contamination sites exist. Check EWG's PFAS map for your area. |
| Iron/Manganese | Moderate risk | Found in some wells depending on local geology. |
How Missouri Compares: Municipal Water Data
CheckMyTap tracks water quality for 15 cities in Missouri. While these numbers reflect municipal water (not private wells), they indicate the baseline mineral content of Missouri's water sources. Private wells often draw from the same aquifers but with less treatment.
| Metric | Missouri Average | National Average |
|---|---|---|
| Hardness | 211 PPM (very hard) | 170 PPM |
| Hardness range | 140 - 299 PPM | 25 - 400+ PPM |
| Lead (avg municipal) | 2 ppb | 3.2 ppb |
| Nitrate (avg municipal) | 0.6 mg/L | 1.1 mg/L |
| Cities with PFAS detected | 10 of 15 | ~45% nationally |
| Cities exceeding PFAS MCL (4 ppt) | 10 |
Hardest water in Missouri: Springfield (299 PPM), Columbia North (290 PPM), Joplin (270 PPM), Columbia (251 PPM), Jefferson City (230 PPM).
Testing Requirements in Missouri
Missouri does not have a statewide mandatory testing requirement for existing private wells. Regardless of state requirements, the EPA recommends testing annually for:
- Every year: Total coliform bacteria, E. coli, nitrate, pH, and total dissolved solids
- At least once: Arsenic, lead, copper, fluoride, and any contaminant identified as a local risk
- Recommended for Missouri: Radon in water (granitic bedrock states have higher risk)
- Recommended for Missouri: PFAS panel, especially if near military bases or industrial sites
- After events: Retest after flooding, well repairs, nearby construction, or any change in taste/color/odor
Recommended Treatment for Missouri Wells
Based on Missouri's geology and common contaminant risks, these treatment systems address the most likely issues:
Missouri groundwater averages 211 PPM. A softener prevents scale damage, reduces energy waste, and extends appliance life
Learn moreKills bacteria and viruses without chemicals. Recommended for all well water systems
Frequently Asked Questions
Is well water in Missouri safe to drink?
Well water quality in Missouri varies significantly by location and geology. Missouri sits on Ozark Plateau karst and glacial drift. No single contaminant dominates statewide, but local conditions vary. The only way to know your specific water quality is to test it. Use our free interpreter to understand your results.
How often should I test my well water in Missouri?
The EPA recommends testing annually for bacteria (total coliform, E. coli), nitrate, total dissolved solids, and pH. Radon testing is also recommended in Missouri. Test more frequently if you notice changes in taste, color, or odor, or after flooding, nearby construction, or well repairs.
Does Missouri require well water testing?
Missouri does not have a statewide mandatory testing requirement for existing private wells. However, the EPA strongly recommends annual testing regardless of state requirements. Your county health department may have additional local requirements.
What is the average water hardness in Missouri?
Municipal water in Missouri averages 211 PPM across 15 cities tracked by CheckMyTap, ranging from 140 to 299 PPM. Private well water typically runs 20-50% harder than city water because groundwater has more contact time with mineral formations. Most Missouri well owners benefit from a water softener. Check your city's data.