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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Water quality data for 4 cities serving 311,298 residents
Jefferson County in Colorado has an average water quality score of 98/100 (Grade A) based on analysis of 4 municipal water systems. The county's water systems serve approximately 311,298 residents.
Overall, Jefferson County demonstrates good water quality standards. 2 of 4 cities exceed the county average, with Wheat Ridge leading with a score of 100/100.
4 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Golden | 100 | A | 38,288 |
| 2 | Wheat Ridge | 100 | A | 20,000 |
| 3 | Arvada Biggest deduction: 4 monitoring/reporting violations in the last 5 years (−4 pts) | 96 | A | 171,610 |
| 4 | Lakewood Biggest deduction: Other PFAS detected in UCMR5 sampling: PFBS 4 ppt, PFPeA 3.5 ppt, PFHxA 3.8 ppt (−6 pts) | 94 | A | 81,400 |
Real EPA readings across county water systems (lead: latest 90th percentile; PFAS: UCMR5 2023–2026; others: 2012–2019 averages)
| Contaminant | Avg Level | Max Level | EPA Limit | % of Limit | Cities |
|---|---|---|---|---|---|
| TTHM (2012–2019 avg) | 34.54 ug/L | 39.137 ug/L | 80 ug/L | 43.2% | 3 |
| HAA5 (2012–2019 avg) | 16.233 ug/L | 29.334 ug/L | 60 ug/L | 27.1% | 3 |
| Fluoride (2012–2019 avg) | 0.557 mg/L | 0.627 mg/L | 4 mg/L | 13.9% | 3 |
| Lead (90th percentile) | 1.7 ppb | 3.1 ppb | 15 ppb | 11.3% | 3 |
| Radium (2012–2019 avg) | 0.244 pCi/L | 0.487 pCi/L | 5 pCi/L | 4.9% | 2 |
| Nitrate (2012–2019 avg) | 0.156 mg/L | 0.238 mg/L | 10 mg/L | 1.6% | 3 |
| Uranium (2012–2019 avg) | 0.182 ug/L | 0.432 ug/L | 30 ug/L | 0.6% | 3 |
| PFAS (PFOA/PFOS max, UCMR5) | 0 ppt | 0 ppt | 4 ppt | 0% | 3 |
Recent violations across county water systems
Health-based: Treatment technique — Treatment Technique No Certif. Operator - Stage 1 Disinfectants and Disinfection Byproducts Rule
2/28/2017
Monitoring & reporting — Monitoring, Turbidity (Enhanced SWTR) - Interim Enhanced Surface Water Treatment Rule
5/31/2024
Monitoring & reporting — Monitoring, Turbidity (Enhanced SWTR) - Interim Enhanced Surface Water Treatment Rule
4/30/2024
Monitoring & reporting — Monitoring of Treatment (SWTR-Filter) - Surface Water Treatment Rule
2/29/2024
Monitoring & reporting — Monitoring of Treatment (SWTR-Filter) - Surface Water Treatment Rule
1/31/2024
Water quality in Jefferson County, Colorado reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 4 municipal water systems serving a combined population of over 311,298 residents.
The county shows strong water quality performance, with scores ranging from 94/100 in Lakewood to 100/100 in Wheat Ridge. This 6-point spread indicates relatively consistent water quality standards across municipal systems.
The most prevalent contaminants detected across Jefferson County water systems include TTHM (2012–2019 avg), HAA5 (2012–2019 avg), Fluoride (2012–2019 avg). Every county-wide average sits below 50% of its EPA Maximum Contaminant Level (MCL).
Jefferson County's water quality is generally good. Residents can feel confident in their tap water quality, though those with specific health concerns or sensitivity to certain contaminants may still benefit from filtration. Regular review of your city's annual Consumer Confidence Report is recommended.
Jefferson County has an average water quality score of 98/100 (Grade A) based on analysis of 4 municipal water systems serving 311,298 residents.
Wheat Ridge has the highest water quality score in Jefferson County at 100/100. View the detailed report for Wheat Ridge.
Most cities in Jefferson County have water that meets EPA standards. However, a water filter can provide additional protection and improve taste. The need depends on your specific city and any personal health considerations.
Click on any city in the rankings table above to view its detailed water quality report, including contaminant levels, EPA compliance history, and filter recommendations.