How hard is the water in Rochester Hills, MI?

Tap water hardness
100mg/L
5.9gpg
Moderately hard

Reported by Rochester Hills · September 2025

MI typical
112 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

Tap water in Rochester Hills has about 100 mg/L of hardness, which is 5.9 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Rochester Hills, dated September 2025.

Rochester Hills on the hardness scale, with nearby cities
060120180240300360+MI typical 112Berkley: 85 mg/LBerkley 85Auburn Hills: 90 mg/LAuburn Hills 90Beverly Hills: 90 mg/LBeverly Hills 90Royal Oak: 96 mg/LRoyal Oak 96Troy: 100 mg/LTroy 100Utica: 103 mg/LUtica 103Sterling Heights: 103 mg/LSterling Heights 103Rochester: 104 mg/LRochester 104Pontiac: 121 mg/LPontiac 121Madison Heights: 277 mg/LMadison Heights 277Rochester Hills 100mg/L as calcium carbonate060120180240300360+MI 112Auburn Hills: 90 mg/LAuburn Hil. 90Troy: 100 mg/LTroy 100Utica: 103 mg/LUtica 103Sterling Heights: 103 mg/LSterling H. 103Rochester: 104 mg/LRochester 104Pontiac: 121 mg/LPontiac 121100 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Rochester Hills sits 12 mg/L below the typical Michigan figure of 112. Of the 10 nearest cities we track, 4 have softer water and 5 have harder. The range nearby runs from 85 mg/L in Berkley to 277 in Madison Heights.

What 100 mg/L means at home

You may see faint white spots on glasses and shower doors after the water dries.

Scale builds up slowly. A kettle or coffee maker needs descaling now and then, maybe every few months.

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

Optional. Plenty of households at this level live with it and descale the kettle now and then.

Water softener

Worth a look if spots on glass bother you, or if your tankless water heater manual asks for softer water.

Carbon filter

Improves taste and removes chlorine. It leaves calcium and magnesium in place.

Softener size for Rochester Hills

3 people × 75 gallons a day × 5.9 gpg = 1,321 grains a day. A 24,000-grain unit regenerates about every 18 days.

Size it for your household

EPA record for Rochester Hills's water system

Rochester Hills · PWSID MI0000325

No health-based violations since 2016

Serves about 74,000 people from surface water.

Health-based
0
Monitoring or reporting
0
Open now
0

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 Rochester Hills water hard?

Somewhat. It measures about 100 mg/L (5.9 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Rochester Hills in grains per gallon?

About 5.9 gpg. One grain per gallon equals 17.1 mg/L, so 100 mg/L divided by 17.1 gives 5.9.

What size water softener do I need in Rochester Hills?

For 3 people using 75 gallons each per day, 5.9 gpg works out to about 1,321 grains a day. A 24,000-grain softener covers that with a regeneration about every 18 days.

Has the Rochester Hills water system had EPA violations?

EPA records show no health-based violations for Rochester Hills since 2016.

Nearby cities

All 118 cities in Michigan

Hardness data: TapWaterData US Water Hardness (utility report, September 19, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.