Portland, OR water hardness
Portland Water Bureau publishes a hardness range of 7 to 11 mg/L for its system, in its Portland Water Bureau 2026 Drinking Water Quality Report. 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:
Bull Run water—Portland's main water supply—is soft. It typically has a total hardness of 7 to 11 parts per million (ppm), or approximately ½ a grain of hardness per gallon.
Portland Water Bureau, Portland Water Bureau 2026 Drinking Water Quality Report
Units as published: ppm, with grains per gallon given alongside. What kind of figure it is: a range with no average. Retrieved 2026-10-16.
Portland 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 | 8.6 | 0.5 | gpg published, mg/L is our conversion |
| Low end of published range | 7 | 0.4 | mg/L published, gpg is our conversion |
| High end of published range | 11 | 0.6 | mg/L published, gpg is our conversion |
| Plotted on the scale above | 9 | 0.5 | midpoint of the published range (no average is published); 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: 9 ÷ 17.1 = 0.5 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 | Portland Water Bureau |
|---|---|
| Service area as published | Portland's main supply is Bull Run; the bureau also runs a groundwater supply it describes as moderately hard at about 80 ppm. Which supply is in service changes, so an address can receive water at either end of that spread at different times of year. |
| Source water | Bull Run watershed (main supply) and the city's groundwater supply. |
A second supply. Portland's groundwater supply is moderately hard: about 80 ppm, or about 5 grains per gallon. That is 80 mg/L, or about 5 gpg, against the main supply plotted above. Which supply reaches an address changes, so this system spans two classifications rather than one.
Provenance of every number on this page
| Source document | Portland Water Bureau 2026 Drinking Water Quality Report |
|---|---|
| Source URL | https://www.portland.gov/water/drinking-water-quality/about-drinking-water-quality/2026-drinking-water-quality-report |
| Published by | Portland Water Bureau |
| Report year | 2025 |
| Year note | The report covers contaminants the bureau detected in its drinking water in 2025. The hardness figures are published as standing descriptions of each supply rather than as a dated table row, and no sample year is attached to them. |
| Retrieved | 2026-10-16 |
| Classification bands | USGS Water Science School, retrieved 2026-10-16 |
Notes the report forces on this page
- The two Portland supplies differ by roughly a factor of eight in hardness. The figure plotted on the scale is the Bull Run range, because the bureau calls it the main supply; the groundwater figure is shown beside it rather than averaged into it.
- No sample year is attached to either figure.
If you are sizing a softener for Portland water
At 0.5 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 Portland 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
- Boston, MA Massachusetts Water Resources Authority (MWRA), 16 mg/L (0.9 gpg)
- Manchester, NH Manchester Water Works, 17.9 mg/L (1 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