PurityMap
Search city, ZIP, contaminant⌘KFind my water
Updated 2026-09-16
State water report

Colorado Water Quality: 92 Cities Ranked by the Records

Water quality across 92 cities in Colorado, drawn from EPA drinking-water records. Each city page shows the measured contaminants and a reproducible Purity Score.

Finding by finding

What Colorado's records show

Counts of cities whose serving system reported each result. There is no statewide score: PurityMap does not average local records into a statewide safety verdict. 2 cities have a past health-based violation on record.

PFAS above a 2024 limit

MCL

7of 92 cities

Cities whose system reported a PFAS above its federal limit.

PFOS in Colorado →

Nitrate above the MCL

MCL

0of 92 cities

Cities whose system reported nitrate above 10 mg/L.

About nitrate →

Hard or very hard

No federal limit

0of 92 cities

Above 120 mg/L as CaCO₃ (7 gpg) on the USGS scale, of 1 cities with a hardness value.

About hard water →
City rankings

Colorado cities ranked by the records

Highest first. A summary of each serving system’s record, not a safety verdict.

  1. 1
    South Adams County WsdSOUTH ADAMS COUNTY WSD · CO0101140
    Report →
  2. 2
    East Cherry Creek Valley WsdEAST CHERRY CREEK VALLEY WSD · CO0103035
    Report →
  3. 3
    GoldenGOLDEN CITY OF · CO0130040
    Report →
  4. 4
    SterlingSTERLING CITY OF · CO0138045
    Report →
  5. 5
    Woodmen Hills MdWOODMEN HILLS MD · CO0121930
    Report →
  6. 6
    Castle Pines North MdCASTLE PINES NORTH MD · CO0118006
    Report →
  7. 7
    Meridian MdMERIDIAN SERVICE MD · CO0121455
    Report →
  8. 8
    TrinidadTRINIDAD CITY OF · CO0136800
    Report →
  9. 9
    AlamosaALAMOSA CITY OF · CO0102100
    Report →
  10. 10
    WestminsterWESTMINSTER CITY OF · CO0101170
    Report →

Showing the top 10 of 92 scored cities.

See all 92 in the table

92 cities, highest Purity Score first

  1. 1South Adams County Wsd
    SOUTH ADAMS COUNTY WSD · PWSID CO0101140 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    PFAS detected, none above a limitDetected
  2. 2East Cherry Creek Valley Wsd
    EAST CHERRY CREEK VALLEY WSD · PWSID CO0103035 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    PFBA 6.2 ng/L detected, no federal or state limitDetected
  3. 3Golden
    GOLDEN CITY OF · PWSID CO0130040 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detectedNot detected
  4. 4Sterling
    STERLING CITY OF · PWSID CO0138045 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detectedNot detected
  5. 5Woodmen Hills Md
    WOODMEN HILLS MD · PWSID CO0121930 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detectedNot detected
  6. 6Castle Pines North Md
    CASTLE PINES NORTH MD · PWSID CO0118006 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    PFAS detected, none above a limitDetected
  7. 7Meridian Md
    MERIDIAN SERVICE MD · PWSID CO0121455 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detectedNot detected
  8. 8Trinidad
    TRINIDAD CITY OF · PWSID CO0136800 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detectedNot detected
  9. 9Alamosa
    ALAMOSA CITY OF · PWSID CO0102100 · Purity Score 100/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detectedNot detected
  10. 10Westminster
    WESTMINSTER CITY OF · PWSID CO0101170 · Purity Score 99/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detected; lead 1.3 µg/LDetected
  11. 11Aspen
    ASPEN CITY OF · PWSID CO0149122 · Purity Score 99/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detected; lead 1 µg/LDetected
  12. 12Left Hand Wd
    LEFT HAND WD · PWSID CO0107471 · Purity Score 99/100 (Excellent) · Confidence: moderate · Assessed at the water-system level
    No PFAS detected; lead 1 µg/LDetected
Showing 12 of 92.

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no state score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works. See how Colorado compares with other states.

By contaminant

PFAS, lead and hard water in Colorado

Counties

Colorado counties

22 counties with city reports
Show all 22 counties
Suppliers

Largest water systems

  • DENVER WATER BOARDDenver · CO0116001 · 1,287,000 served
  • AURORA CITY OFAurora · CO0103005 · 533,407 served
  • COLORADO SPRINGS UTILITIESColorado Springs · CO0121150 · 464,111 served
  • THORNTON CITY OFThornton · CO0101150 · 226,465 served
  • WESTMINSTER CITY OFWestminster · CO0101170 · 202,078 served
  • FT COLLINS CITY OFFt Collins · CO0135291 · 179,901 served
All water systems →
Full indexAll 92 Colorado city reports, A–Z
Next step

State patterns can’t tell you what reaches your tap.

Find my water
Learn

Learn your supplier

Resolve your address to the one public water system that serves it.

Find my water →
Test

Test your own tap

Plumbing inside a building can add lead and change what reaches your glass.

How to test →
Solve

Treat by concern

Only after a city report names a finding, match a treatment certified for it.

Treatment options →
Questions

Colorado water, frequently asked

FOLLOW COLORADO WATER RECORDS

Get Colorado updates

We'll email you when Colorado records change, such as new PFAS or lead results.

Double opt-in: we email a confirmation link. Unsubscribe anytime. No spam.

How does Colorado tap water compare across cities?

PurityMap ranks 92 cities in Colorado by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is South Adams County Wsd's main water system: SOUTH ADAMS COUNTY WSD · PWSID CO0101140 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Colorado cities have PFAS above the federal limit?

7 cities of 92 had at least one regulated PFAS (PFOA, PFOS or PFHxS) measured above the 2024 federal limit in EPA's UCMR 5 testing, including Widefield Wsd (PFOS 15.8 ng/L), Brighton (PFOS 10.6 ng/L), Thornton (PFOA 7.1 ng/L). PFAS were detected at any level in 20.

Is there lead in Colorado tap water?

Utilities report lead as a 90th-percentile result from home taps. 63 of 92 Colorado cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

Have Colorado water systems had drinking-water violations?

2 cities in Colorado have a health-based violation in the federal SDWIS record within about the last ten years. Each city report lists the contaminant, year and whether it was resolved.

Does Colorado have hard water?

Hardness is published in utility water-quality reports for 1 Colorado city on record; the hardest is Denver at 6.1 grains per gallon. Hardness affects scale and appliances; it is not a health finding.

Limits, sources and corrections

A statewide page cannot tell you what reaches a specific address. Water quality varies by supplier, sampling period and household plumbing; open a city report for the evidence behind a local result.

Sources: EPA UCMR 5 (PFAS, 2024), SDWIS Lead and Copper Rule 90th-percentile results and health-based violations, and utility Consumer Confidence Reports where on file. Every city report links its dated source records.

Updated 2026-09-16. How PurityMap analyzes water data · Report an error