Boston, MA water hardness
Massachusetts Water Resources Authority (MWRA) publishes a hardness of 16 mg/L (1 grain per gallon, also its own figure) for its system, on the page cited below. On the USGS scale that is soft water.
The published figure, exactly as it appears
This is the hardness line transcribed from the source, with nothing added:
MWRA's drinking water has a hardness of approximately 16 milligrams per liter, or 1 grain per gallon.
Massachusetts Water Resources Authority (MWRA)
Units as published: mg/L, with gpg given alongside. What kind of figure it is: a single value. Retrieved 2026-10-16.
Boston hardness in mg/L and grains per gallon
Water-quality reports use mg/L (identical to ppm). Softener instructions and plumbing specifications use grains per gallon. Both are below. Where a figure is our arithmetic rather than the utility's own number, it says so.
| Figure | mg/L (ppm) | Grains per gallon | Whose number |
|---|---|---|---|
| Published average | 16 | 1 | both published by the utility |
| Plotted on the scale above | 16 | 0.9 | published average; the gpg here is our conversion at 17.1, so it can differ slightly from a utility’s own rounded gpg figure |
The conversion, both ways: gpg = mg/L ÷ 17.1 and mg/L = gpg × 17.1. Worked for this system: 16 ÷ 17.1 = 0.9 gpg. The converter does °dH and °f as well, and why the factor is 17.1 explains where the number comes from.
What this figure does not tell you
Service area and source water
| Utility | Massachusetts Water Resources Authority (MWRA) |
|---|---|
| Service area as published | MWRA supplies drinking water to 53 communities, some only partially, and three more through the Chicopee Valley Aqueduct. Your own town's water department may blend MWRA water with local sources, so a partially supplied community is not described by this figure. |
| Source water | The Quabbin and Wachusett Reservoirs (per MWRA's 2025 annual test results page). |
Provenance of every number on this page
| Source document | MWRA, Frequently Asked Questions About MWRA Tap Water, 'Is MWRA Drinking Water Hard or Soft?' |
|---|---|
| Source URL | https://www.mwra.com/your-water-system/drinking-water-quality/frequently-asked-questions-about-mwra-tap-water |
| Published by | Massachusetts Water Resources Authority |
| Report year | Not stated on the source page |
| Year note | MWRA publishes this figure as a standing statement on its FAQ page with no sampling year attached. The MWRA 2025 Annual Water Quality Test Results page for fully supplied communities was also read on 2026-10-16; no hardness line was found in the portion read. |
| Retrieved | 2026-10-16 |
| Classification bands | USGS Water Science School, retrieved 2026-10-16 |
Notes the report forces on this page
- MWRA states the figure as approximate and attaches no year or range to it.
- MWRA states plainly that its drinking water is soft; this is the softest system on this site.
If you are sizing a softener for Boston water
At 1 gpg, the sizing arithmetic starts from your household's water use, not from the hardness alone. The calculator below is pre-filled with this system's figure and every other input is an editable assumption.
Whether a softener is worth installing at this hardness is a judgement, not arithmetic, and it is not one this site makes for you. Nothing here has been tested by the author.
Where Boston sits against other verified systems
- Portland, OR 9 mg/L 0.5 gpg Soft
- Boston, MA 16 mg/L 1 gpg Soft
- Manchester, NH 17.9 mg/L 1 gpg Soft
- New York, NY 32 mg/L 2 gpg Soft
- Austin, TX 93 mg/L 5.4 gpg Moderately hard
- Denver, CO 105 mg/L 6.1 gpg Moderately hard
- Phoenix, AZ 237 mg/L 13.9 gpg Very hard
- Las Vegas, NV 280 mg/L 16 gpg Very hard
- San Antonio, TX 299.3 mg/L 17.5 gpg Very hard
- Indianapolis, IN 317 mg/L 19 gpg Very hard
mg/L as calcium carbonate. Each classification band is drawn the same width, so the axis is not linear in mg/L.
Systems with similar published hardness
- Manchester, NH Manchester Water Works, 17.9 mg/L (1 gpg)
- Portland, OR Portland Water Bureau, 9 mg/L (0.5 gpg)
- New York, NY New York City Department of Environmental Protection (NYC DEP), 32 mg/L (1.9 gpg)
- Austin, TX Austin Water, 93 mg/L (5.4 gpg)
All 10 verified systems How to find hardness in your own utility's report If you are on a well instead