waterbycounty

Colorado Water Quality

Drinking water data for all 64 counties.

Avg Water Score

38.7

State Grade

F

Counties with Data

64

of 64 total

All Colorado Counties

CountyWater Score
Cheyenne County86.0
Crowley County86.0
Custer County86.0
Gilpin County86.0
Hinsdale County86.0
Jackson County86.0
Lake County86.0
Mineral County86.0
San Juan County86.0
Denver County71.8
Arapahoe County69.8
Mesa County68.0
Broomfield County64.6
Adams County60.4
Boulder County56.1
Weld County55.2
Montezuma County54.6
Jefferson County54.0
Summit County54.0
Douglas County52.5
Las Animas County51.8
El Paso County51.3
Eagle County49.9
Pitkin County49.7
Moffat County47.7
Larimer County46.6
Grand County43.5
Yuma County41.5
Fremont County39.1
Lincoln County37.4
Elbert County37.0
Chaffee County36.9
La Plata County34.0
Saguache County33.8
Archuleta County33.3
Kit Carson County33.1
Logan County27.7
Rio Blanco County27.1
Gunnison County26.5
Montrose County25.8
Rio Grande County23.9
Pueblo County22.2
Morgan County20.1
Washington County19.7
Phillips County19.0
Routt County18.0
Conejos County17.7
Sedgwick County16.3
Garfield County16.2
Costilla County14.2
San Miguel County10.7
Clear Creek County10.3
Delta County10.3
Ouray County8.3
Alamosa County7.2
Park County7.2
Teller County6.1
Dolores County5.2
Huerfano County4.9
Kiowa County4.3
Bent County2.7
Baca County1.6
Prowers County0.8
Otero County0.5

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Frequently Asked Questions

Which county in Colorado has the best water quality?
Cheyenne County has the highest water quality score in Colorado at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in Colorado has the most water violations?
Otero County has among the lowest water quality scores in Colorado at 0.5/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in Colorado?
Colorado has an average water quality score of 38.7/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.
What contaminants are found in Colorado water supplies?
Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.

Data Source

Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

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