Water hardness by state
How hard is the water in Colorado?
Tap water in Colorado averages 11.6 grains per gallon (198 ppm calcium carbonate). That number determines how fast limescale coats your water heater, shower glass and appliances.
Based on 368 measurements from 187 monitoring sites, 2018-02 → 2023-10.
Water hardness by county in Colorado
Medians of the individual measurements recorded in each county. Hardness varies far more within a state than between neighbouring states — this is where your own figure actually comes from.
| County | gpg | mg/L | Range (mg/L) | Classification |
|---|---|---|---|---|
| El Paso County | 6.4 | 110 | 64–226 | Soft water |
| Larimer County | 0.3 | 5 | 4–6 | Soft water |
| Elbert County | 13.5 | 230 | 223–647 | Moderately hard water |
| Boulder County | 12.9 | 221 | 5–394 | Moderately hard water |
| Gunnison County | 9.6 | 164 | 42–223 | Moderately hard water |
| Otero County | 44.9 | 767 | 488–944 | Very hard water |
| Routt County | 23.6 | 404 | 382–492 | Very hard water |
| Rio Blanco County | 2.8 | 48 | 33–121 | Soft water |
| Arapahoe County | 114.6 | 1960 | 530–1970 | Very hard water |
| Eagle County | 10.1 | 172 | 129–847 | Moderately hard water |
| Custer County | 6.3 | 108 | 87–173 | Soft water |
| Garfield County | 70.2 | 1200 | 21–1350 | Very hard water |
Range shown is the 10th-90th percentile of local measurements. Counties with fewer than five samples are omitted rather than estimated.
What 11.6 gpg means in Colorado
At this level limescale builds up slowly but steadily. White traces appear on faucets and shower glass within months, and the water heater loses a little efficiency every year. Light protection already pays off.
What it does to your home
Water heater: even a thin layer of scale insulates the heating element and drives energy use up.
Appliances: dishwashers, washing machines and coffee makers scale up and fail years early.
Fixtures and skin: white spots on faucets and glass, dry skin and dull hair after every shower.
How this figure was obtained
Median of the site-level medians at 187 groundwater monitoring sites (wells and springs — the sources most US public systems draw from) in the USGS National Water Information System (368 individual measurements, 2018-02 → 2023-10). Each site is collapsed to one value first so that a heavily sampled location cannot skew the state figure; the range shown is the 10th-90th percentile across sites. This describes the raw water resource, not a specific municipal tap after treatment.
Water Quality Portal — USGS National Water Information System (NWIS), characteristic "Hardness, Ca, Mg"Statewide average — hardness varies by utility and season. Always verify with your local water quality report.
Frequently asked questions — Colorado
Is 11.6 gpg considered hard water?
On the US scale, 0–3.5 gpg is soft, 3.5–7 gpg moderately hard, 7–10.5 gpg hard and above 10.5 gpg very hard. At 11.6 gpg (198 ppm), water in Colorado is classified as Moderately hard water.
Does Colorado have a limescale problem?
Water in Colorado averages 11.6 gpg — Moderately hard water. The harder the water, the faster calcium carbonate deposits build up in water heaters, appliances and pipes. Below 3.5 gpg the risk is minimal; above 7 gpg scale becomes a running cost.
How do I find the exact water hardness at my address in Colorado?
Check your utility's annual water quality report (Consumer Confidence Report) or your water bill, or use our free interactive hardness map. Hardness can vary widely between neighboring utilities in Colorado.
Do I need a salt-based water softener at 11.6 gpg?
Not necessarily. Salt softeners add sodium to your water and need constant refills. LIMPEO treats limescale with an electromagnetic field — no salt, no chemicals, no maintenance — and keeps healthy minerals in your drinking water.