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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 18 cities serving 1,031,858 residents
Middlesex County in Massachusetts has an average water quality score of 90/100 (Grade A) based on analysis of 18 municipal water systems. The county's water systems serve approximately 1,031,858 residents.
Overall, Middlesex County demonstrates good water quality standards. 11 of 18 cities exceed the county average, with Watertown leading with a score of 100/100.
18 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Framingham | 100 | A | 72,362 |
| 2 | Arlington | 100 | A | 46,308 |
| 3 | Marlborough | 100 | A | 41,799 |
| 4 | Watertown | 100 | A | 35,985 |
| 5 | Waltham Biggest deduction: 1 monitoring/reporting violation in the last 5 years (−1 pts) | 99 | A | 65,218 |
| 6 | Belmont Biggest deduction: 1 monitoring/reporting violation in the last 5 years (−1 pts) | 99 | A | 27,442 |
| 7 | Newton Biggest deduction: 2 monitoring/reporting violations in the last 5 years (−2 pts) | 98 | A | 88,931 |
| 8 | Malden Biggest deduction: Lead 90th-percentile tap result 9.74 ppb for 2026-01-01–2026-06-30, below the 15 ppb action level (−3 pts) | 97 | A | 66,263 |
| 9 | Everett Biggest deduction: Lead 90th-percentile tap result 5.67 ppb for 2025-01-01–2025-12-31, below the 15 ppb action level (−3 pts) | 97 | A | 49,075 |
| 10 | Reading Biggest deduction: Lead 90th-percentile tap result 8.39 ppb for 2021-01-01–2023-12-31, below the 15 ppb action level (−3 pts) | 96 | A | 26,262 |
| 11 | Burlington Biggest deduction: 2 monitoring/reporting violations in the last 5 years (−2 pts) | 96 | A | 25,864 |
| 12 | Lowell Biggest deduction: PFOA detected at up to 4.6 ppt in UCMR5 sampling (2023-12-13), at or above EPA's 4 ppt MCL (−10 pts) | 85 | B | 120,418 |
| 13 | Wakefield Biggest deduction: PFOA detected at up to 6.9 ppt in UCMR5 sampling (2026-05-28), at or above EPA's 4 ppt MCL (−10 pts) | 85 | B | 27,090 |
| 14 | Cambridge Biggest deduction: PFOA detected at up to 4.8 ppt in UCMR5 sampling (2024-06-12), at or above EPA's 4 ppt MCL (−10 pts) | 83 | B | 118,214 |
| 15 | Somerville Biggest deduction: 1 health-based violation still unresolved with EPA/state (−20 pts) | 80 | B | 81,045 |
| 16 | Woburn Biggest deduction: PFOA detected at up to 8.4 ppt in UCMR5 sampling (2025-10-14), at or above EPA's 4 ppt MCL (−10 pts) | 74 | C | 40,876 |
| 17 | Natick Biggest deduction: PFOA detected at up to 14.3 ppt in UCMR5 sampling (2025-06-11), at or above EPA's 4 ppt MCL (−10 pts) | 74 | C | 37,006 |
| 18 | Medford Biggest deduction: 2 health-based violations (MCL/treatment-technique) in the last 5 years (−20 pts) | 57 | F | 61,700 |
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) | 3.444 ppt | 37.3 ppt | 4 ppt | 86.1% | 18 |
| TTHM (2012–2019 avg) | 30.312 ug/L | 41.003 ug/L | 80 ug/L | 37.9% | 7 |
| Lead (90th percentile) | 3.474 ppb | 9.74 ppb | 15 ppb | 23.2% | 18 |
| HAA5 (2012–2019 avg) | 13.636 ug/L | 27.067 ug/L | 60 ug/L | 22.7% | 7 |
| Fluoride (2012–2019 avg) | 0.735 mg/L | 0.898 mg/L | 4 mg/L | 18.4% | 7 |
| Nitrate (2012–2019 avg) | 0.462 mg/L | 1.294 mg/L | 10 mg/L | 4.6% | 7 |
| Arsenic (2012–2019 avg) | 0.322 ug/L | 1 ug/L | 10 ug/L | 3.2% | 7 |
Recent violations across county water systems
Health-based: Treatment technique — Lead Service Line Replacement (LSLR) - Lead and Copper Rule
10/31/2023
Health-based: Treatment technique — Lead Service Line Replacement (LSLR) - Lead and Copper Rule
6/30/2023
Health-based: Treatment technique — Lead Service Line Replacement (LSLR) - Lead and Copper Rule
10/31/2019
Health-based: MCL exceeded — Maximum Contaminant Level Violation, E. coli (RTCR) - Revised Total Coliform Rule
9/30/2019
Health-based: Treatment technique — WQP Entry Point/Tap Treatment Technique Non-Compliance - Lead and Copper Rule
6/30/2017
Health-based: Treatment technique — Treatment Technique No Certif. Operator - Stage 1 Disinfectants and Disinfection Byproducts Rule
2/29/2016
Showing 10 of 20 recent violations
Water quality in Middlesex County, Massachusetts reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 18 municipal water systems serving a combined population of over 1,031,858 residents.
The county shows strong water quality performance, with scores ranging from 57/100 in Medford to 100/100 in Watertown. This 43-point spread indicates significant variation in water quality across the county, suggesting different water sources or treatment approaches.
The most prevalent contaminants detected across Middlesex County water systems include PFAS (PFOA/PFOS max, UCMR5), TTHM (2012–2019 avg), Lead (90th percentile). At least one reading averages above 50% of its EPA limit across the county's systems, worth attention from residents and utilities.
Middlesex 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.
Middlesex County has an average water quality score of 90/100 (Grade A) based on analysis of 18 municipal water systems serving 1,031,858 residents.
Watertown has the highest water quality score in Middlesex County at 100/100. View the detailed report for Watertown.
Most cities in Middlesex 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.