How hard is the water in Royal Oak, MI?

Tap water hardness
96mg/L
5.6gpg
Moderately hard

Reported by Royal Oak, City of · August 2025

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

Tap water in Royal Oak has about 96 mg/L of hardness, which is 5.6 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Royal Oak, City of, dated August 2025.

Royal Oak on the hardness scale, with nearby cities
060120180240300360+MI typical 112Berkley: 85 mg/LBerkley 85Hamtramck: 87 mg/LHamtramck 87Beverly Hills: 90 mg/LBeverly Hills 90Warren: 95 mg/LWarren 95Detroit: 96 mg/LDetroit 96Ferndale: 100 mg/LFerndale 100Troy: 100 mg/LTroy 100Sterling Heights: 103 mg/LSterling Heights 103Madison Heights: 277 mg/LMadison Heights 277Oak Park: 277 mg/LOak Park 277Royal Oak 96mg/L as calcium carbonate060120180240300360+MI 112Berkley: 85 mg/LBerkley 85Beverly Hills: 90 mg/LBeverly Hi. 90Ferndale: 100 mg/LFerndale 100Troy: 100 mg/LTroy 100Madison Heights: 277 mg/LMadison He. 277Oak Park: 277 mg/LOak Park 27796 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 96 mg/L, Royal Oak is 16 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 96 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 Royal Oak

3 people × 75 gallons a day × 5.6 gpg = 1,267 grains a day. A 24,000-grain unit regenerates about every 18 days.

Size it for your household

EPA record for Royal Oak's water system

Royal Oak, City of · PWSID MI0005830

No health-based violations since 2016

Serves about 57,236 people from surface water.

Health-based
0
Monitoring or reporting
4
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 Royal Oak water hard?

Somewhat. It measures about 96 mg/L (5.6 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Royal Oak in grains per gallon?

About 5.6 gpg. One grain per gallon equals 17.1 mg/L, so 96 mg/L divided by 17.1 gives 5.6.

What size water softener do I need in Royal Oak?

For 3 people using 75 gallons each per day, 5.6 gpg works out to about 1,267 grains a day. A 24,000-grain softener covers that with a regeneration about every 18 days.

Has the Royal Oak water system had EPA violations?

EPA records show no health-based violations for Royal Oak, City of since 2016. There were also 4 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 118 cities in Michigan

Hardness data: TapWaterData US Water Hardness (utility report, August 31, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.