Water hardness in Boston
0.8 gpg soft
Tap water in Boston is soft: 0.8 gpg (13 mg/L · 0.7 °dH · 1.3 °fH).
Source: MWRA Drinking Water Quality - Water and Health (2025 data) (2025) · data checked 2026-10-19
Range across supply zones: 11–16 mg/L.
Boston is served by MWRA water, with the Boston Water and Sewer Commission handling local delivery. MWRA's 2025 data show 13.1 mg/L (0.8 gpg) for the metro system, with a range of 11 to 15.6 mg/L. It is soft water from the Quabbin and Wachusett reservoirs. Scale is negligible, and a softener has no benefit.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 0.8 gpg |
|---|---|
| Utility | Massachusetts Water Resources Authority (MWRA) wholesale; Boston Water and Sewer Commission (BWSC) retail |
How Boston compares
- Tap water in Boston is 92 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1351 of 1372 in the United States (1 = hardest); 1 % of these cities have softer water.
- In Massachusetts it is number 10 of 13 cities; the regional median is 1.9 gpg.
- Nearest city with clearly harder water: Cambridge, 4 km away (4.2 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Little or no limescale in kettles, water heaters or washing machines.
- Soap lathers easily; water does not dry skin or hair.
- Dishwasher: salt setting at minimum or off.
- No softener needed; a jug filter only changes taste.
How much salt will you use for softening?
No. Water this soft does not need softening.
Descale a coffee machine or kettle about every 6 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Boston
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 1 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Boston water hard or soft?
It is soft: 13 mg/L as CaCO₃ (0.8 gpg, 0.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Boston safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Boston water?
0.8 gpg, equal to 0.7 °dH, 1.3 °fH or 13 mg/L calcium carbonate.
What dishwasher salt setting should I use in Boston?
For 13 mg/L (0.7 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Boston?
No. With soft water a softener adds nothing.
Source
Source: MWRA Drinking Water Quality - Water and Health (2025 data) (2025). Method: figure published by the water supplier. MWRA Drinking Water Quality - Water and Health (2025 data) · Outdated figure? Tell us