Denver, CO water hardness
Denver Water publishes an average hardness of 105.009 mg/L for its system, in its Denver Water 2026 Water Quality Report, data collected throughout 2025. On the USGS scale that is moderately hard water.
The published figure, exactly as it appears
This is the hardness line transcribed from the source, with nothing added:
Total Hardness | 2025 | Quarterly | 105,009 | 55,000–124,000 | ppb | Erosion of natural deposits.
Denver Water, Denver Water 2026 Water Quality Report, data collected throughout 2025
Units as published: ppb. What kind of figure it is: an average with a range. Retrieved 2026-10-16.
Denver 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 | 105.009 | 6.1 | mg/L published, gpg is our conversion |
| Low end of published range | 55 | 3.2 | mg/L published, gpg is our conversion |
| High end of published range | 124 | 7.3 | mg/L published, gpg is our conversion |
| Plotted on the scale above | 105 | 6.1 | 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: 105 ÷ 17.1 = 6.1 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 | Denver Water |
|---|---|
| Service area as published | Denver Water states a total water service area of approximately 300 square miles. Its hardness page adds that the southern collection system is considered moderately hard and the northern collection system somewhat soft, so one system figure covers water of two different characters. |
Provenance of every number on this page
| Source document | Denver Water 2026 Water Quality Report, data collected throughout 2025 |
|---|---|
| Source URL | https://www.denverwater.org/your-water/water-quality/water-quality-reports/2026-report |
| Published by | Denver Water |
| Report year | 2025 |
| Year note | Hardness sits in the table 'Additional water quality parameters sampled in the distribution system', sampling frequency quarterly, year 2025, in the report Denver Water titles its 2026 Water Quality Report. |
| Retrieved | 2026-10-16 |
| Classification bands | USGS Water Science School, retrieved 2026-10-16 |
Notes the report forces on this page
- Denver Water publishes this row in parts per billion, not mg/L. The mg/L figures shown on this site are the published ppb values divided by 1,000, which is a definitional unit change (1 mg/L = 1,000 ppb), not a re-measurement. The average therefore carries the published precision: 105,009 ppb is 105.009 mg/L.
- Denver Water's hardness page states that its water is slightly harder in winter and softer from late spring through autumn when runoff dilutes the minerals, which is one reason the published range spans 55 to 124 mg/L.
- Denver Water's own hardness page quotes the USGS classes but publishes no single Denver number; the number here comes from the water quality report table.
If you are sizing a softener for Denver water
At 6.1 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 Denver 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
- Austin, TX Austin Water, 93 mg/L (5.4 gpg)
- New York, NY New York City Department of Environmental Protection (NYC DEP), 32 mg/L (1.9 gpg)
- Manchester, NH Manchester Water Works, 17.9 mg/L (1 gpg)
- Boston, MA Massachusetts Water Resources Authority (MWRA), 16 mg/L (0.9 gpg)
All 10 verified systems How to find hardness in your own utility's report If you are on a well instead