How hard is the water in Wellesley, MA?

Tap water hardness
89mg/L
5.2gpg
Moderately hardReports range 89–114

Reported by Natick Water Department · October 2025

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

Wellesley water measures 89 mg/L (5.2 gpg) of hardness, moderately hard by USGS standards. The number comes from Natick Water Department, dated October 2025. Reports for this system disagree, with values from 89 to 114 mg/L.

Wellesley on the hardness scale, with nearby cities
060120180240300360+MA typical 38Watertown: 16 mg/LWatertown 16Belmont: 16 mg/LBelmont 16Waltham: 17 mg/LWaltham 17Brookline: 19 mg/LBrookline 19Newton: 32 mg/LNewton 32Framingham: 52 mg/LFramingham 52Cochituate: 93 mg/LCochituate 93Medfield: 95 mg/LMedfield 95Needham: 96 mg/LNeedham 96Dedham: 110 mg/LDedham 110Wellesley 89mg/L as calcium carbonate060120180240300360+MA 38Watertown: 16 mg/LWatertown 16Waltham: 17 mg/LWaltham 17Newton: 32 mg/LNewton 32Cochituate: 93 mg/LCochituate 93Needham: 96 mg/LNeedham 96Dedham: 110 mg/LDedham 11089 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 89 mg/L, Wellesley is 51 mg/L above the typical Massachusetts figure of 38. Of the 10 nearest cities we track, 6 have softer water and 4 have harder. The range nearby runs from 16 mg/L in Watertown to 110 in Dedham.

What 89 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 Wellesley

3 people × 75 gallons a day × 5.2 gpg = 1,166 grains a day. A 24,000-grain unit regenerates about every 20 days.

Size it for your household

EPA record for Wellesley's water system

Wellesley Water Division · PWSID MA3317000

No health-based violations since 2016

Serves about 29,550 people from surface water.

Health-based
0
Monitoring or reporting
1
Open now
0

EPA lists Wellesley Water Division as the system serving Wellesley. The hardness figure above comes from a different system's report, which TapWaterData uses for Wellesley.

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 Wellesley water hard?

Somewhat. It measures about 89 mg/L (5.2 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Wellesley in grains per gallon?

About 5.2 gpg. One grain per gallon equals 17.1 mg/L, so 89 mg/L divided by 17.1 gives 5.2.

What size water softener do I need in Wellesley?

For 3 people using 75 gallons each per day, 5.2 gpg works out to about 1,166 grains a day. A 24,000-grain softener covers that with a regeneration about every 20 days.

Has the Wellesley water system had EPA violations?

EPA records show no health-based violations for Wellesley Water Division since 2016. There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.

Nearby cities

All 104 cities in Massachusetts

Hardness data: TapWaterData US Water Hardness (utility report, October 7, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.