How hard is the water in Dedham, MA?

Tap water hardness
110mg/L
6.4gpg
Moderately hard

Reported by Dedham Westwood Water Dist. · September 2025

MA typical
38 mg/L
EPA health violations since 2016
1
Softener for 3 people
24k grain
Data
Utility report

The water in Dedham carries roughly 110 mg/L of dissolved calcium and magnesium, or 6.4 grains per gallon. That is moderately hard water. The number comes from Dedham Westwood Water Dist., dated September 2025.

Dedham on the hardness scale, with nearby cities
060120180240300360+MA typical 38Watertown: 16 mg/LWatertown 16Brookline: 19 mg/LBrookline 19Newton: 32 mg/LNewton 32Milton: 44 mg/LMilton 44Norwood: 46 mg/LNorwood 46Walpole: 66 mg/LWalpole 66Randolph: 68 mg/LRandolph 68Wellesley: 89 mg/LWellesley 89Medfield: 95 mg/LMedfield 95Needham: 96 mg/LNeedham 96Dedham 110mg/L as calcium carbonate060120180240300360+MA 38Brookline: 19 mg/LBrookline 19Newton: 32 mg/LNewton 32Milton: 44 mg/LMilton 44Norwood: 46 mg/LNorwood 46Wellesley: 89 mg/LWellesley 89Needham: 96 mg/LNeedham 96110 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Dedham sits 72 mg/L above the typical Massachusetts figure of 38. None of the 10 nearest cities we track has harder water. The range nearby runs from 16 mg/L in Watertown to 96 in Needham.

What 110 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 Dedham

3 people × 75 gallons a day × 6.4 gpg = 1,444 grains a day. A 24,000-grain unit regenerates about every 16 days.

Size it for your household

EPA record for Dedham's water system

Dedham Westwood Water Dist. · PWSID MA3073000

1 health-based violation since 2016

Serves about 41,630 people from surface water.

Health-based
1
Monitoring or reporting
0
Open now
0
20162017201820192020202120222023202420252026Total trihalomethanes (TTHM)'16'18'20'22'24'26Total trihalomethanes (TTHM)
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Total trihalomethanes (TTHM)a disinfection byproduct12021Resolved

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 Dedham water hard?

Somewhat. It measures about 110 mg/L (6.4 grains per gallon), which the USGS classes as moderately hard.

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

About 6.4 gpg. One grain per gallon equals 17.1 mg/L, so 110 mg/L divided by 17.1 gives 6.4.

What size water softener do I need in Dedham?

For 3 people using 75 gallons each per day, 6.4 gpg works out to about 1,444 grains a day. A 24,000-grain softener covers that with a regeneration about every 16 days.

Has the Dedham water system had EPA violations?

EPA records show 1 health-based violation for Dedham Westwood Water Dist. since 2016, involving Total trihalomethanes (TTHM).

Nearby cities

All 104 cities in Massachusetts

Hardness data: TapWaterData US Water Hardness (utility report, September 22, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.