How hard is the water in Cambridge, MA?

Tap water hardness
60mg/L
3.5gpg
Moderately hardReports range 25–60

Reported by Cambridge Water Department · September 2025

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

Tap water in Cambridge has about 60 mg/L of hardness, which is 3.5 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Cambridge Water Department, dated September 2025. Reports for this system disagree, with values from 25 to 60 mg/L.

Cambridge on the hardness scale, with nearby cities
060120180240300360+MA typical 38Watertown: 16 mg/LWatertown 16Belmont: 16 mg/LBelmont 16Everett: 16 mg/LEverett 16Chelsea: 16 mg/LChelsea 16Arlington: 17 mg/LArlington 17Brookline: 19 mg/LBrookline 19Somerville: 20 mg/LSomerville 20Winchester: 20 mg/LWinchester 20Medford: 21 mg/LMedford 21Malden: 25 mg/LMalden 25Cambridge 60mg/L as calcium carbonate060120180240300360+MA 38Watertown: 16 mg/LWatertown 16Belmont: 16 mg/LBelmont 16Arlington: 17 mg/LArlington 17Brookline: 19 mg/LBrookline 19Somerville: 20 mg/LSomerville 20Medford: 21 mg/LMedford 2160 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Cambridge sits 22 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 25 in Malden.

What 60 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 Cambridge

3 people × 75 gallons a day × 3.5 gpg = 792 grains a day. A 24,000-grain unit regenerates about every 30 days.

Size it for your household

EPA record for Cambridge's water system

Cambridge Water Department · PWSID MA3049000

No health-based violations since 2016

Serves about 118,214 people from surface water.

Health-based
0
Monitoring or reporting
31
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 Cambridge water hard?

Somewhat. It measures about 60 mg/L (3.5 grains per gallon), which the USGS classes as moderately hard.

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

About 3.5 gpg. One grain per gallon equals 17.1 mg/L, so 60 mg/L divided by 17.1 gives 3.5.

What size water softener do I need in Cambridge?

For 3 people using 75 gallons each per day, 3.5 gpg works out to about 792 grains a day. A 24,000-grain softener covers that with a regeneration about every 30 days.

Has the Cambridge water system had EPA violations?

EPA records show no health-based violations for Cambridge Water Department since 2016. There were also 31 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 104 cities in Massachusetts

Hardness data: TapWaterData US Water Hardness (utility report, September 15, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.