Denver
Denver, United States has an estimated water hardness of 105 ppm (mg/L as calcium carbonate), which is classed as moderately hard. Some mineral build-up is possible in heated appliances.
Denver water hardness in every unit
| Unit | Reference estimate |
|---|---|
| mg/L or ppm (CaCO₃) | 105 |
| mmol/L | 1.05 |
| German degrees (°dH) | 5.88 |
| French degrees (°fH) | 10.5 |
| Clark degrees (°e) | 7.37 |
| Grains per US gallon (gpg) | 6.13 |
Published range: 55–124 ppm.
How the Denver figure was derived
- Period covered: 2025-01-01 – 2025-12-31
- Calculation: The average is the figure the source publishes for this period.
Where Denver's water comes from
- Supplier: Denver Water
- Source: Denver Water’s northern and southern collection systems
- Official website: Denver Water
The 2025 distribution-system average was about 105 mg/L, with quarterly results from 55 to 124 mg/L. Hardness is an aesthetic matter, not a health concern. Denver Water: 2026 Water Quality Report (checked 2026-10-31).
How Denver compares
With a reference estimate of 105 ppm, Denver ranks 32nd hardest of the 69 cities in our directory, 31 ppm above the directory median of 74 ppm. Among the cities in our directory in North America, San Antonio is the hardest at 299 ppm and Portland is the softest at 9 ppm.
What the range means
Published figures for Denver run from 55 to 124 ppm. That is a wide spread (69 ppm), so the figure at your own tap could differ a lot from the average. Supply zones, blending of different water sources, and the time of year can all move it. A test strip or your utility's postcode lookup is worth the extra step here.
What moderately hard water means at home
Moderately hard water can leave light white deposits on kettle elements, taps and glassware over time. It is usually manageable with periodic descaling, and many households need no softening equipment at all.
Using a 105 ppm reading with your appliances
- Dishwasher: salt check manual; match the converted reading to your model. Use salt only as specified for the built-in softener.
- Coffee machine: descale when the manual or machine indicates; filter: use only a compatible filter specified by the manufacturer.
- Laundry: use the medium-water dose. Follow the product label for your load size.
- Kettle: Inspect for scale; follow the manual.
- Humidifier: For ultrasonic or impeller units, use low-mineral water such as distilled water. Empty and dry portable tanks daily; clean every third day. Follow manufacturer instructions.
Official manufacturer guidance
Use these references with your exact appliance model. They explain settings and maintenance, not the local water measurement. Source languages and model limits are shown; these are not affiliate links.
- Bosch US — Dishwasher salt and the low-salt indicator (en-US)
Salt and scale guidance for dishwashers equipped with a salt reservoir; it does not mean every US dishwasher uses salt.
- Bosch US — How to clean and descale Bosch dishwashers (en-US)
Cleaning and descaling procedures for Bosch dishwashers, with care-product instructions.
(checked 2026-10-20).
Hardness alone does not determine maintenance frequency. How to match your reading to an appliance manual. Dishwasher settings by brand: find your setting. Thinking about a softener? Pros and cons and sizing. Kettles and coffee machines: descaling guide. Portable humidifier care: US EPA guidance.
Frequently asked questions
Do I need dishwasher salt in Denver?
Check manual. Use salt only as specified for the built-in softener. Always follow your dishwasher manual.
How often should I descale a coffee machine in Denver?
Descale when the manual or machine indicates. Hardness alone does not determine an interval: usage and appliance design also matter. Water filter: use only a compatible filter specified by the manufacturer.
Do I need a water softener in Denver?
Usually not. Appliance settings and occasional descaling are normally enough, but a filter or softener is a personal choice if you dislike spotting.
Is hard water in Denver safe to drink?
Water hardness is mainly an aesthetic and scale issue. The World Health Organization does not set a health-based guideline value for it. Hardness affects taste, scale and detergent use rather than drinking safety, and your utility is responsible for meeting drinking-water standards. If you have a specific health or dietary concern, ask your doctor.
How to check your own water
City averages are a starting point. To get your actual figure, check the linked source (Denver Water: 2026 Water Quality Report (2025 data)) and obtain a current report for your address from your water supplier, or dip a hardness test strip in a glass of cold tap water and read it against the chart. Strips usually report in °dH, gpg or ppm; enter the number into the Waterdial checker to convert it and see the matching appliance settings. Use a recent, correctly performed hardness test when a city estimate is too broad.
Source
Denver Water: 2026 Water Quality Report (2025 data), checked 2026-10-31. Guidance is general; your appliance manual takes priority.
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