Hard water in Union, MO
Calculated from the utility's calcium and magnesium results · June 2024
- MO typical
- 121 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Calculated from utility data
Union water measures 188 mg/L (11.0 gpg) of hardness, very hard by USGS standards. TapWaterData worked it out from the calcium and magnesium levels the local utility reports (June 2024). Reports for this system disagree, with values from 135 to 244 mg/L.
Union sits 67 mg/L above the typical Missouri figure of 121. Of the 10 nearest cities we track, 4 have softer water and 5 have harder. The range nearby runs from 79 mg/L in Eureka to 307 in Warrenton.
What 188 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 188 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 × 11.0 gpg = 2,477 grains a day. A 24,000-grain unit regenerates about every 9 days.
EPA record for Union's water system
No health-based violations since 2016
Serves about 12,348 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 3
- Open now
- 0
EPA lists this system as serving Union.
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 Union water hard?
Yes. It measures about 188 mg/L (11.0 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Union in grains per gallon?
About 11.0 gpg. One grain per gallon equals 17.1 mg/L, so 188 mg/L divided by 17.1 gives 11.0.
What size water softener do I need in Union?
For 3 people using 75 gallons each per day, 11.0 gpg works out to about 2,477 grains a day. A 24,000-grain softener covers that with a regeneration about every 9 days.
Has the Union water system had EPA violations?
EPA records show no health-based violations for Union PWS since 2016. There were also 3 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Washington210 mg/LVery hard
- Pacific197 mg/LVery hard
- Sullivan188 mg/LVery hard
- Eureka79 mg/LModerately hard
- Lake St. Louis123 mg/LHard
- Ballwin242 mg/LVery hard
- Chesterfield121 mg/LHard
- Wright City306 mg/LVery hard
- Warrenton307 mg/LVery hard
- Murphy104 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (calculated from utility data, June 19, 2024), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.