Jefferson County Water Quality: 2 Cities Ranked by the Records
Jefferson County, Colorado: 2 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
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 2 systems10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest35.5 µg/L
- GOLDEN CITY OF35.5 µg/LSample date: 2023-02-14 to 2023-11-07
- ARVADA CITY OF9.6 µg/LSample date: 2023-03-06 to 2024-02-26
Lead (90th percentile)Detected in 1 system of 2 tested15 µg/L federal action level · US EPAHighest3.1 µg/L
- ARVADA CITY OF3.1 µg/LMonitoring period: 2023–2025
- GOLDEN CITY OFNot detectedMonitoring period: 2023–2025
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest3.2 gpg
- ARVADA CITY OF3.2 gpgReporting year: 2026
29 PFAS tested, none detected in any systemShow
Tested in these 2 systems: ARVADA CITY OF, GOLDEN CITY 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)
Cities ranked by the records
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.
0of 2 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 Colorado1city reports hardness · Arvada, 3.2 gpg
None above 7 gpg, the USGS threshold for hard water. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
Frequently asked
How does Jefferson County tap water compare across cities?
PurityMap ranks 2 cities in Jefferson 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 Golden's main water system: GOLDEN CITY OF · PWSID CO0130040 · 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 Jefferson County cities had a PFAS sample above a 2024 EPA limit?
None of the 2 Jefferson 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 Jefferson County tap water?
Utilities report lead as a 90th-percentile result from home taps. 1 of 2 Jefferson 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.
Does Jefferson County have hard water?
Hardness is published in utility water-quality reports for 1 Jefferson County city on record; the hardest is Arvada at 3.2 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
Follow Jefferson County's water
Get an email when a city record in the county changes.
Record changes only
We email when places in Jefferson County get new results. Unsubscribe any time.
Follow Jefferson County's water →