Watertown, MA water hardness

Tap water hardness
16mg/L
0.9gpg
Soft

Reported by Watertown Water Dept. (MWRA) · July 2025

MA typical
38 mg/L
EPA health violations since 2016
0
Data
Utility report

Watertown water measures 16 mg/L (0.9 gpg) of hardness, soft by USGS standards. The number comes from Watertown Water Dept. (MWRA), dated July 2025.

Watertown on the hardness scale, with nearby cities
060120180240300360+MA typical 38Belmont: 16 mg/LBelmont 16Arlington: 17 mg/LArlington 17Waltham: 17 mg/LWaltham 17Brookline: 19 mg/LBrookline 19Somerville: 20 mg/LSomerville 20Winchester: 20 mg/LWinchester 20Medford: 21 mg/LMedford 21Newton: 32 mg/LNewton 32Lexington: 33 mg/LLexington 33Cambridge: 60 mg/LCambridge 60Watertown 16mg/L as calcium carbonate060120180240300360+MA 38Belmont: 16 mg/LBelmont 16Arlington: 17 mg/LArlington 17Waltham: 17 mg/LWaltham 17Brookline: 19 mg/LBrookline 19Newton: 32 mg/LNewton 32Cambridge: 60 mg/LCambridge 6016 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Watertown sits 22 mg/L below the typical Massachusetts figure of 38. None of the 10 nearest cities we track has softer water. The range nearby runs from 16 mg/L in Belmont to 60 in Cambridge.

What 16 mg/L means at home

Soap and shampoo lather with very little product. Kettles and showerheads stay mostly free of white crust.

Some people notice that soap feels slow to rinse off in soft water. That slippery feel is normal and harmless.

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

Nothing, as far as hardness goes. At 16 mg/L a softener would have almost nothing to remove.

Carbon filter

If the water tastes of chlorine, a pitcher or faucet carbon filter takes care of that. It does not change hardness.

EPA record for Watertown's water system

Watertown Department of Public Works · PWSID MA3314000

No health-based violations since 2016

Serves about 35,985 people from surface water.

Health-based
0
Monitoring or reporting
1
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 Watertown water hard?

No. It measures about 16 mg/L (0.9 grains per gallon), which the USGS classes as soft.

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

About 0.9 gpg. One grain per gallon equals 17.1 mg/L, so 16 mg/L divided by 17.1 gives 0.9.

Has the Watertown water system had EPA violations?

EPA records show no health-based violations for Watertown Department of Public Works 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, July 27, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.