Loading water data...
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 15 cities serving 3,850,739 residents
Maricopa County in Arizona has an average water quality score of 81/100 (Grade B) based on analysis of 15 municipal water systems. The county's water systems serve approximately 3,850,739 residents.
Overall, Maricopa County demonstrates good water quality standards. 8 of 15 cities exceed the county average, with Paradise Valley leading with a score of 98/100.
15 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Paradise Valley Biggest deduction: 2 monitoring/reporting violations in the last 5 years (−2 pts) | 98 | A | 14,107 |
| 2 | Queen Creek Biggest deduction: Nitrate (as N): 1 of 144 finished-water samples (2012–2019) above the 10 mg/l MCL (0.7% of samples); max 14 mg/l (−3 pts) | 96 | A | 95,502 |
| 3 | Glendale Biggest deduction: 3 monitoring/reporting violations in the last 5 years (−3 pts) | 95 | A | 234,766 |
| 4 | Surprise Biggest deduction: Arsenic: 1 of 128 finished-water samples (2012–2019) above the 10 ug/l MCL (0.8% of samples); max 10.8 ug/l (−3 pts) | 95 | A | 40,007 |
| 5 | Scottsdale Biggest deduction: 4 monitoring/reporting violations in the last 5 years (−4 pts) | 94 | A | 241,361 |
| 6 | Buckeye Biggest deduction: 4 monitoring/reporting violations in the last 5 years (−4 pts) | 93 | A | 30,377 |
| 7 | Phoenix Biggest deduction: Other PFAS detected in UCMR5 sampling: PFBS 16 ppt, PFBA 6 ppt (−4 pts) | 91 | A | 1,695,000 |
| 8 | Chandler Biggest deduction: 77 monitoring/reporting violations in the last 5 years (−10 pts) | 84 | B | 247,328 |
| 9 | Peoria Biggest deduction: PFOA detected at up to 5.6 ppt in UCMR5 sampling (2025-12-08), at or above EPA's 4 ppt MCL (−10 pts) | 76 | C | 187,676 |
| 10 | El Mirage Biggest deduction: PFOA detected at up to 4 ppt in UCMR5 sampling (2024-05-23), at or above EPA's 4 ppt MCL (−10 pts) | 72 | C | 39,884 |
| 11 | Mesa Biggest deduction: 25 monitoring/reporting violations in the last 5 years (−10 pts) | 71 | C | 466,000 |
| 12 | Tempe Biggest deduction: PFOA detected at up to 38.7 ppt in UCMR5 sampling (2025-03-18), at or above EPA's 4 ppt MCL (−10 pts) | 71 | C | 165,000 |
| 13 | Avondale Biggest deduction: PFOA detected at up to 13.5 ppt in UCMR5 sampling (2025-01-08), at or above EPA's 4 ppt MCL (−10 pts) | 68 | D | 96,130 |
| 14 | Gilbert Biggest deduction: 79 monitoring/reporting violations in the last 5 years (−10 pts) | 61 | D | 247,600 |
| 15 | Goodyear Biggest deduction: 34 monitoring/reporting violations in the last 5 years (−10 pts) | 54 | F | 50,001 |
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 |
|---|---|---|---|---|---|
| PFAS (PFOA/PFOS max, UCMR5) | 7.06 ppt | 55.8 ppt | 4 ppt | 176.5% | 15 |
| Arsenic (2012–2019 avg) | 5.172 ug/L | 7.857 ug/L | 10 ug/L | 51.7% | 15 |
| Nitrate (2012–2019 avg) | 3.745 mg/L | 7.016 mg/L | 10 mg/L | 37.5% | 15 |
| TTHM (2012–2019 avg) | 30.026 ug/L | 50.838 ug/L | 80 ug/L | 37.5% | 15 |
| Fluoride (2012–2019 avg) | 0.536 mg/L | 1.439 mg/L | 4 mg/L | 13.4% | 15 |
| HAA5 (2012–2019 avg) | 7.961 ug/L | 16.747 ug/L | 60 ug/L | 13.3% | 15 |
| Uranium (2012–2019 avg) | 2.563 ug/L | 4.844 ug/L | 30 ug/L | 8.5% | 13 |
| Lead (90th percentile) | 1.16 ppb | 5.01 ppb | 15 ppb | 7.7% | 15 |
Recent violations across county water systems
Health-based: Treatment technique — Single Turbidity Exceed (Enhanced SWTR) - Interim Enhanced Surface Water Treatment Rule
12/31/2020
Health-based: Treatment technique — Failure Submit Treatment Requirement Rpt - Long Term 2 Enhanced Surface Water Treatment Rule
9/30/2017
Showing 10 of 20 recent violations
Water quality in Maricopa County, Arizona reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 15 municipal water systems serving a combined population of over 3,850,739 residents.
The county shows strong water quality performance, with scores ranging from 54/100 in Goodyear to 98/100 in Paradise Valley. This 44-point spread indicates significant variation in water quality across the county, suggesting different water sources or treatment approaches.
The most prevalent contaminants detected across Maricopa County water systems include PFAS (PFOA/PFOS max, UCMR5), Arsenic (2012–2019 avg), Nitrate (2012–2019 avg). At least one reading averages above 50% of its EPA limit across the county's systems, worth attention from residents and utilities.
Maricopa 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.
Maricopa County has an average water quality score of 81/100 (Grade B) based on analysis of 15 municipal water systems serving 3,850,739 residents.
Paradise Valley has the highest water quality score in Maricopa County at 98/100. View the detailed report for Paradise Valley.
Most cities in Maricopa 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.