Weld County Water Quality: 8 Cities Ranked by the Records

Name: Weld County Water Quality Data (2026)
Creator: PurityMap
License: https://creativecommons.org/licenses/by/4.0/

Weld County, Colorado: 8 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my system Open on the map Private wells in Weld County

Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

LithiumDetected in 1 system of 8 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest25.7 µg/L

GREELEY CITY OF25.7 µg/LSample date: 2023-05-24 to 2024-05-22
ERIE TOWN OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2024-05-06 to 2025-02-10
EVANS CITY OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-12-06 to 2024-07-22
FIRESTONE TOWN OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-02-23 to 2023-10-30
FREDERICK TOWN OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2025-01-15 to 2025-10-07
JOHNSTOWN TOWN OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-02-16 to 2023-11-07
SEVERANCE TOWN OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2025-01-06 to 2025-10-07
WINDSOR TOWN OFNot detected · below 9.0 µg/L lab reporting limitSample date: 2023-08-07 to 2024-05-13

Lead (90th percentile)Detected in 8 systems15 µg/L federal action level · US EPAHighest5.8 µg/L

WINDSOR TOWN OF5.8 µg/LMonitoring period: 2023–2025
GREELEY CITY OF4 µg/LMonitoring period: 2025–2025
FIRESTONE TOWN OF3.6 µg/LMonitoring period: 2024–2024
FREDERICK TOWN OF2.9 µg/LMonitoring period: 2023–2025
ERIE TOWN OF2.6 µg/LMonitoring period: 2025–2025
EVANS CITY OF2.4 µg/LMonitoring period: 2026–2028 (still open)
SEVERANCE TOWN OF2 µg/LMonitoring period: 2023–2025
JOHNSTOWN TOWN OF1 µg/LMonitoring period: 2025–2025

29 PFAS tested, none detected in any systemShow

Tested in these 8 systems: ERIE TOWN OF, EVANS CITY OF, FIRESTONE TOWN OF, FREDERICK TOWN OF, GREELEY CITY OF, JOHNSTOWN TOWN OF, SEVERANCE TOWN OF, WINDSOR TOWN OF

11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
Perfluoro-3-methoxypropanoic acid (PFMPA)
Perfluoro-4-methoxybutanoic acid (PFMBA)
Perfluorobutanesulfonic acid (PFBS)
Perfluorobutanoic acid (PFBA)
Perfluorodecanoic acid (PFDA)
Perfluorododecanoic acid (PFDoA)
Perfluoroheptanesulfonic acid (PFHpS)
Perfluoroheptanoic acid (PFHpA)
Perfluorohexanesulfonic acid (PFHxS)
Perfluorohexanoic acid (PFHxA)
Perfluorononanoic acid (PFNA)
Perfluorooctanesulfonic acid (PFOS)
Perfluorooctanoic acid (PFOA)
Perfluoropentanesulfonic acid (PFPeS)
Perfluoropentanoic acid (PFPeA)
Perfluorotetradecanoic acid (PFTA)
Perfluorotridecanoic acid (PFTrDA)
Perfluoroundecanoic acid (PFUnA)

8 cities

Cities ranked by the records

1
SeveranceSEVERANCE TOWN OF
No PFAS detectedLead below action level
Open city report →
2
ErieERIE TOWN OF
No PFAS detectedLead below action level
Open city report →
3
EvansEVANS CITY OF
No PFAS detectedLead below action level
Open city report →
4
FrederickFREDERICK TOWN OF
No PFAS detectedLead below action level
Open city report →
5
FirestoneFIRESTONE TOWN OF
No PFAS detectedLead below action level
Open city report →
6
JohnstownJOHNSTOWN TOWN OF
No PFAS detectedLead below action level
Open city report →
7
GreeleyGREELEY CITY OF
No PFAS detectedLead below action level
Open city report →
8
WindsorWINDSOR TOWN OF
No PFAS detectedLead below action level
Open city report →

Showing 6 of 8 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county 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.

PFAS in Weld CountyPFAS detected in 0 of 8 cities; none had a sample above a 2024 EPA limit

4.0 ng/L federal MCL · PFOS, ng/LPFAS in Colorado

Lead

0of 8 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in Colorado

Who supplies the county

Largest water systems

GreeleyGREELEY CITY OF · CO0162321
132,310 served
ErieERIE TOWN OF · CO0162255
47,444 served
FirestoneFIRESTONE TOWN OF · CO0162476
27,798 served
JohnstownJOHNSTOWN TOWN OF · CO0162418
27,295 served
WindsorWINDSOR TOWN OF · CO0162843
23,500 served
EvansEVANS CITY OF · CO0162260
19,369 served
FrederickFREDERICK TOWN OF · CO0162288
17,173 served
SeveranceSEVERANCE TOWN OF · CO0162707
11,733 served

Questions

Frequently asked

How does Weld County tap water compare across cities?

PurityMap ranks 8 cities in Weld County 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 Severance's main water system: SEVERANCE TOWN OF · PWSID CO0162707 · Purity Score 98 (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 Weld County cities had a PFAS sample above a 2024 EPA limit?

None of the 8 Weld County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing. PFAS were detected below the limit in 0.

Is there lead in Weld County tap water?

Utilities report lead as a 90th-percentile result from home taps. 8 of 8 Weld County 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.

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