Hard water in Port Huron, MI
County estimate from 232 water samples in St. Clair County · July 2026
- MI typical
- 112 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 32k grain
- Data
- County estimate
Water samples from around Port Huron put hardness at about 300 mg/L (17.5 gpg), which would be very hard on the USGS scale. Treat this as a rough guide: it is the median of 232 samples taken across St. Clair County, mostly wells and streams, not a test of Port Huron's treated tap water. One more reason for caution: EPA lists Port Huron's water system as using surface water, which is often softer than the wells behind the county figure.
Port Huron sits 188 mg/L above the typical Michigan figure of 112. None of the 10 nearest cities we track has harder water. The range nearby runs from 101 mg/L in Fraser to 165 in New Haven.
What 300 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 300 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 × 17.5 gpg = 3,946 grains a day. A 32,000-grain unit regenerates about every 8 days.
EPA record for Port Huron's water system
No health-based violations since 2016
Serves about 28,983 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 2
- Open now
- 0
EPA lists this system as serving Port Huron.
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 Port Huron water hard?
Yes. It measures about 300 mg/L (17.5 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Port Huron in grains per gallon?
About 17.5 gpg. One grain per gallon equals 17.1 mg/L, so 300 mg/L divided by 17.1 gives 17.5.
What size water softener do I need in Port Huron?
For 3 people using 75 gallons each per day, 17.5 gpg works out to about 3,946 grains a day. A 32,000-grain softener covers that with a regeneration about every 8 days.
Has the Port Huron water system had EPA violations?
EPA records show no health-based violations for Port Huron, City of since 2016. There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Marysville113 mg/LModerately hard
- New Haven165 mg/LHard
- New Baltimore136 mg/LHard
- Mount Clemens103 mg/LModerately hard
- Utica103 mg/LModerately hard
- Rochester104 mg/LModerately hard
- Fraser101 mg/LModerately hard
- Sterling Heights103 mg/LModerately hard
- St. Clair Shores101 mg/LModerately hard
- Roseville101 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (county estimate, July 4, 2026), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.