Arapahoe County Water Quality: 2 Cities Ranked by the Records
Arapahoe 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 EPAHighest24.9 µg/L
- ENGLEWOOD CITY OF24.9 µg/LSample date: 2024-07-11 to 2025-04-22
- AURORA CITY OF21.4 µg/LSample date: 2023-01-24 to 2024-08-05
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest8 gpg
- AURORA CITY OF8 gpgReporting year: 2026
Perfluorooctanoic acid (PFOA)Detected in 1 system of 2 tested4.0 ng/L federal MCL (2024) · US EPAHighest4 ng/L
- ENGLEWOOD CITY OF4 ng/LSample date: 2024-07-11 to 2025-04-22
- AURORA CITY OFNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-01-24 to 2024-08-05
Lead (90th percentile)Detected in 2 systems15 µg/L federal action level · US EPAHighest5 µg/L
- ENGLEWOOD CITY OF5 µg/LMonitoring period: 2026–2026 (still open)
- AURORA CITY OF4.7 µg/LMonitoring period: 2026–2026 (still open)
Perfluorobutanesulfonic acid (PFBS)Detected in 2 systems2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest5.8 ng/L
- ENGLEWOOD CITY OF5.8 ng/LSample date: 2024-07-11 to 2025-04-22
- AURORA CITY OF3.3 ng/LSample date: 2023-01-24 to 2024-08-05
Perfluorohexanoic acid (PFHxA)Detected in 2 systems400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest5.6 ng/L
- AURORA CITY OF5.6 ng/LSample date: 2023-01-24 to 2024-08-05
- ENGLEWOOD CITY OF5.5 ng/LSample date: 2024-07-11 to 2025-04-22
Perfluorobutanoic acid (PFBA)Detected in 2 systemsNo federal or state limit; shown for transparencyHighest7.8 ng/L
- AURORA CITY OF7.8 ng/LSample date: 2023-01-24 to 2024-08-05
- ENGLEWOOD CITY OF6.4 ng/LSample date: 2024-07-11 to 2025-04-22
Perfluoropentanoic acid (PFPeA)Detected in 2 systemsNo federal or state limit; shown for transparencyHighest7.2 ng/L
- AURORA CITY OF7.2 ng/LSample date: 2023-01-24 to 2024-08-05
- ENGLEWOOD CITY OF5.8 ng/LSample date: 2024-07-11 to 2025-04-22
24 PFAS tested, none detected in any systemShow
Tested in these 2 systems: AURORA CITY OF, ENGLEWOOD 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)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Perfluorooctanesulfonic acid (PFOS)
- Perfluoropentanesulfonic acid (PFPeS)
- 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 · Aurora, 8 gpg
Hard on the USGS scale. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
Frequently asked
How does Arapahoe County tap water compare across cities?
PurityMap ranks 2 cities in Arapahoe 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 Aurora's main water system: AURORA CITY OF · PWSID CO0103005 · Purity Score 94 (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 Arapahoe County cities had a PFAS sample above a 2024 EPA limit?
None of the 2 Arapahoe 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 2.
Is there lead in Arapahoe County tap water?
Utilities report lead as a 90th-percentile result from home taps. 2 of 2 Arapahoe 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.
Have Arapahoe County water systems had drinking-water violations?
1 city in Arapahoe County has 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 Arapahoe County have hard water?
Hardness is published in utility water-quality reports for 1 Arapahoe County city on record; the hardest is Aurora at 8 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
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