Colorado Water Quality Report 2026

12 cities3,497,978 residentsUpdated March 2026

B83.5/100State Average
Colorado has 12 cities in our database, serving approximately 3,497,978 residents. The average PurityMap score is 83.5/100 (Grade: B), which is 5.6 points above the US average of 77.9/100. Denver has the cleanest water (85/100) while Colorado Springs scores lowest (70/100) due to PFAS detected.
Is Colorado Tap Water Safe to Drink?
Safe — Filtration Recommended

Colorado tap water is safe — filtration recommended based on our analysis of 12 water systems serving 3,497,978 residents. The average PurityMap score is 83.5/100 (Grade: B), which is 5.6 points above the national average.

  • PFAS detected in 1 of 12 cities (8%). Forever chemicals require reverse osmosis filtration.
Our Recommendation

We recommend an under-sink reverse osmosis system for drinking water in PFAS-affected areas of Colorado. RO removes 99%+ of PFAS, lead, and other contaminants. For hard water cities, add a whole-house softener.

All 12 cities in Colorado meet EPA federal drinking water standards as of 2026. However, EPA standards set legal limits — not health goals. Many contaminants are detected at levels that are legal but may still pose long-term health risks according to independent health organizations like the EWG.
Colorado at a Glance
83.5Avg Purity Score
2.6Avg Hardness (GPG)
Soft
1Cities with PFAS
0Cities with Hard Water
1.6Avg Lead (ppb)
76Avg TDS (ppm)

Colorado is 5.6 points above the US average of 77.9/100. Hardness is 3.7 GPG below the US average of 6.3 GPG.

Best & Worst Water in Colorado
Cleanest

Denver

85/100

Source: South Platte River and mountain reservoirs

Most Concerns

Colorado Springs

70/100

PFAS detected

Cities with Most Water Concerns in Colorado

Cities ranked by lowest score. Click any city for the full report and filter recommendations.

RankCityScoreHardnessLeadKey Issues
1Colorado Springs 70/1003.6 GPG1.5 ppbPFAS (1.9 ppt)
2Pueblo 82/1004.8 GPG2.0 ppbHardness 4.8 GPG, Lead 2.0 ppb
3Denver 85/1002.0 GPG1.8 ppbScore: 85/100
4Aurora 85/1002.3 GPG1.6 ppbScore: 85/100
5Fort Collins 85/1002.6 GPG1.2 ppbScore: 85/100
6Lakewood 85/1002.0 GPG1.8 ppbScore: 85/100
7Thornton 85/1002.2 GPG1.5 ppbScore: 85/100
8Westminster 85/1002.1 GPG1.6 ppbScore: 85/100
9Arvada 85/1002.2 GPG1.5 ppbScore: 85/100
10Centennial 85/1002.4 GPG1.8 ppbScore: 85/100
Score Distribution

How Colorado's 12 cities score on the PurityMap 0–100 scale:

Excellent (85–100)
10 cities
Good (70–84)
2 cities
Moderate (60–69)
0 cities
Poor (below 60)
0 cities
Largest Cities in Colorado — Water Quality

Water quality for the most populated cities. Click any city for details.













CityPopulationScoreHardnessKey Issues
Denver1.5M 85/1002.0 GPG—
Colorado Springs479K 70/1003.6 GPGPFAS
Aurora386K 85/1002.3 GPG—
Fort Collins164K 85/1002.6 GPG—
Lakewood156K 85/1002.0 GPG—
Thornton136K 85/1002.2 GPG—
Arvada124K 85/1002.2 GPG—
Westminster116K 85/1002.1 GPG—
Pueblo111K 82/1004.8 GPG—
Centennial110K 85/1002.4 GPG—
Greeley109K 85/1003.5 GPG—
Boulder106K 85/1001.8 GPG—
Hard Water in Colorado

Colorado generally has soft to moderate water. Average: 2.6 GPG (Soft). Most residents do not need a softener.

PFAS in Colorado Water

PFAS have been detected in 1 of 12 cities (8%) in Colorado. Highest: Colorado Springs at 1.9 ppt. Affected: Colorado Springs. A reverse osmosis filter is recommended.

PFAS Guide RO for PFAS
Lead in Colorado Water

All Colorado cities have lead below 5 ppb. Average: 1.6 ppb. Individual homes with older plumbing may have higher levels.

Water Sources in Colorado

Where Colorado gets its drinking water, based on 12 water systems.



Source TypeCities% of Total
Surface Water1083%
Other217%
Recommended Filter for Colorado

1 cities have PFAS. Reverse osmosis is the most effective solution.

All Colorado Cities — Ranked
#CityPop.ScoreHardnessLeadPFASTDS
1Colorado Springs479K 70/1003.6 GPG (Moderate)1.5 ppb⚠️ Yes (1.9 ppt)100 ppm
2Pueblo111K 82/1004.8 GPG (Moderate)2.0 ppb✅ No160 ppm
3Aurora386K 85/1002.3 GPG (Soft)1.6 ppb✅ No65 ppm
4Denver1.5M 85/1002.0 GPG (Soft)1.8 ppb✅ No55 ppm
5Fort Collins164K 85/1002.6 GPG (Soft)1.2 ppb✅ No75 ppm
6Lakewood156K 85/1002.0 GPG (Soft)1.8 ppb✅ No55 ppm
7Thornton136K 85/1002.2 GPG (Soft)1.5 ppb✅ No60 ppm
8Westminster116K 85/1002.1 GPG (Soft)1.6 ppb✅ No58 ppm
9Arvada124K 85/1002.2 GPG (Soft)1.5 ppb✅ No60 ppm
10Centennial110K 85/1002.4 GPG (Soft)1.8 ppb✅ No65 ppm
11Boulder106K 85/1001.8 GPG (Soft)1.2 ppb✅ No48 ppm
12Greeley109K 85/1003.5 GPG (Soft)1.5 ppb✅ No110 ppm
Water Utilities in Colorado

Colorado has 11 utilities. Major: Denver Water, Colorado Springs Utilities, Aurora Water, Fort Collins Utilities, City of Thornton Water.

Sources: South Platte River and mountain reservoirs, Pikes Peak snowmelt and Southern Delivery System, South Platte River and reservoirs, Cache la Poudre River, South Platte River.

Frequently Asked Questions
Which city has the best water in Colorado?
Denver scores highest at 85/100. Source: South Platte River and mountain reservoirs.
Which city has the worst water in Colorado?
Colorado Springs scores lowest at 70/100 due to PFAS detected.
Is Colorado water hard or soft?
Average hardness: 2.6 GPG (Soft). 3.7 GPG below the US average of 6.3 GPG. 0 of 12 cities have hard/very hard water.
Has PFAS been found in Colorado water?
PFAS have been detected in 1 of 12 cities (8%) in Colorado. Highest: Colorado Springs at 1.9 ppt. Affected: Colorado Springs. A reverse osmosis filter is recommended.
What water filter should I use in Colorado?
1 cities have PFAS. Reverse osmosis is the most effective solution.
How does Colorado water compare to the US average?
Score: 83.5/100 (5.6 points above US avg 77.9). Hardness: 2.6 GPG (3.7 GPG below US avg 6.3).
Where does Colorado get its drinking water?Where does Colorado get its drinking water?
Colorado water comes from: Surface Water: 10 cities (83%), Other: 2 cities (17%).
Data Sources & Methodology
  • EPA Safe Drinking Water Information System
  • EWG Tap Water Database
  • State utility Consumer Confidence Reports
  • USGS regional water monitoring data

PurityMap compiles publicly available data and does not perform independent testing.

How we analyze water Data sources
All Colorado Cities with Water Reports

12 city water quality reports available for Colorado.

12 Reports
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Showing all 12 cities
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