Water hardness in Denver
6.1 gpg moderately hard
Tap water in Denver is moderately hard: 6.1 gpg (105 mg/L · 5.9 °dH · 10.5 °fH).
Source: Denver Water 2026 Annual Water Quality Report (2025 data) (2026) · data checked 2026-10-19
Range across supply zones: 55–124 mg/L.
Denver Water's 2026 report, covering 2025 data, gives a quarterly average of 105 mg/L (6.1 gpg) with a range of 55 to 124 mg/L. The report has one system-wide row and no zone split. Denver Water's own hardness page describes the southern system as moderately hard and the northern one as somewhat softer, so the figure at your tap depends on where you live.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 6.1 gpg |
|---|---|
| Utility | Denver Water |
How Denver compares
- Tap water in Denver is 32 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 988 of 1372 in the United States (1 = hardest); 28 % of these cities have softer water.
- In Colorado it is number 6 of 11 cities; the regional median is 6.1 gpg.
- Nearest city with clearly softer water: Broomfield, 22 km away (4.8 gpg).
- Nearest city with clearly harder water: Aurora, 14 km away (7.9 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Denver
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 6 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
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 Denver water hard or soft?
It is moderately hard: 105 mg/L as CaCO₃ (6.1 gpg, 5.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Denver 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 Denver water?
6.1 gpg, equal to 5.9 °dH, 10.5 °fH or 105 mg/L calcium carbonate.
What dishwasher salt setting should I use in Denver?
For 105 mg/L (5.9 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Denver?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Denver Water 2026 Annual Water Quality Report (2025 data) (2026). Method: figure published by the water supplier. Denver Water 2026 Annual Water Quality Report (2025 data) · Outdated figure? Tell us