Hard water in De Soto, MO
Calculated from the utility's calcium and magnesium results · July 2025
- MO typical
- 121 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 32k grain
- Data
- Calculated from utility data
Tap water in De Soto has about 312 mg/L of hardness, which is 18.3 grains per gallon. On the USGS scale that counts as very hard. TapWaterData worked it out from the calcium and magnesium levels the local utility reports (July 2025).
At 312 mg/L, De Soto is 191 mg/L above the typical Missouri figure of 121. Of the 10 nearest cities we track, 7 have softer water and 3 have harder. The range nearby runs from 79 mg/L in Eureka to 565 in Park Hills.
What 312 mg/L means at home
Scale forms fast here. Kettles and coffee makers need regular descaling, and showerheads clog unless you clean them.
Tank water heaters collect mineral sediment that insulates the water from the burner, so flushing the tank matters more than usual.
Dishes and glass shower doors spot easily. Soap scum and a dull film on hair or laundry are common complaints.
Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.
What to do about it
At 312 mg/L most of the trouble is scale, and only a few things deal with it.
Ion-exchange water softener
The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.
Salt-free conditioner
No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.
Reverse osmosis or carbon filter
Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.
3 people × 75 gallons a day × 18.3 gpg = 4,108 grains a day. A 32,000-grain unit regenerates about every 7 days.
EPA record for De Soto's water system
No health-based violations since 2016
Serves about 6,400 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
EPA lists this system as serving De Soto.
Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.
Questions
Is De Soto water hard?
Yes. It measures about 312 mg/L (18.3 grains per gallon), which the USGS classes as very hard.
What is the water hardness in De Soto in grains per gallon?
About 18.3 gpg. One grain per gallon equals 17.1 mg/L, so 312 mg/L divided by 17.1 gives 18.3.
What size water softener do I need in De Soto?
For 3 people using 75 gallons each per day, 18.3 gpg works out to about 4,108 grains a day. A 32,000-grain softener covers that with a regeneration about every 7 days.
Has the De Soto water system had EPA violations?
EPA records show no health-based violations for Desoto PWS since 2016.
Nearby cities
- Festus247 mg/LVery hard
- Herculaneum346 mg/LVery hard
- Pevely308 mg/LVery hard
- Bonne Terre339 mg/LVery hard
- Arnold212 mg/LVery hard
- Park Hills565 mg/LVery hard
- Murphy104 mg/LModerately hard
- Eureka79 mg/LModerately hard
- Pacific197 mg/LVery hard
- Farmington276 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (calculated from utility data, July 30, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.