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Updated 2026-10-15
County water report

Middlesex County Water Quality: 24 Cities Ranked by the Records

Middlesex County, Massachusetts: 24 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my systemOpen on the mapPrivate wells in Middlesex County
Across the county's systems

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.

Perfluorooctanesulfonic acid (PFOS)Detected in 6 systems of 24 tested4.0 ng/L federal MCL (2024) · US EPAHighest37.3 ng/L
Perfluorooctanoic acid (PFOA)Detected in 13 systems of 24 tested4.0 ng/L federal MCL (2024) · US EPAHighest14.3 ng/L
Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 24 tested10 ng/L federal MCL (2024) · US EPAHighest11.2 ng/L
Lead (90th percentile)Detected in 22 systems of 24 tested15 µg/L federal action level · US EPAHighest8 µg/L
Perfluorobutanesulfonic acid (PFBS)Detected in 8 systems of 24 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest9.4 ng/L
Perfluorohexanoic acid (PFHxA)Detected in 13 systems of 24 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest6.1 ng/L
Perfluorobutanoic acid (PFBA)Detected in 9 systems of 24 testedNo federal or state limit; shown for transparencyHighest11 ng/L
Perfluoroheptanoic acid (PFHpA)Detected in 1 system of 24 testedNo federal or state limit; shown for transparencyHighest4 ng/L
1 more contaminant detectedShow
Perfluoropentanoic acid (PFPeA)Detected in 16 systems of 24 testedNo federal or state limit; shown for transparencyHighest10 ng/L
22 substances tested, none detected in any systemShow

Tested in these 24 systems: ASHLAND WATER AND SEWER DEPT., BEDFORD WATER DEPT., BILLERICA WATER WORKS, BURLINGTON WATER DEPT, CAMBRIDGE WATER DEPARTMENT, CONCORD WATER DEPT, HOLLISTON WATER DEPARTMENT, HOPKINTON WATER DEPARTMENT, HUDSON WATER SUPPLY, LOWELL REGIONAL WATER UTILITY, MARLBOROUGH DPW WATER DIV. (MWRA), MAYNARD DPW, WATER DIVISION, NATICK WATER AND SEWER DIVISION, NORTH READING WATER DEPT., TEWKSBURY WATER DEPARTMENT, WAKEFIELD WATER DEPT, WALTHAM WATER DEPARTMENT, WATERTOWN DEPARTMENT OF PUBLIC WORKS, WAYLAND WATER DEPARTMENT, WESTFORD WATER DEPARTMENT, WESTON WATER DEPT., WILMINGTON WATER DEPT, WINCHESTER WATER DEPT, WOBURN WATER DEPT.

  • 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)
  • Lithium
  • 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)
  • Perfluorononanoic acid (PFNA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
24 cities

Cities ranked by the records

Showing 6 of 24 cities · scores are system-level, not tap tests

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.

PFAS in Middlesex County13 of 24 city reports had a PFAS sample above a 2024 EPA limit
  1. Natick37.3 ng/L
  2. Woburn6.9 ng/L
  3. Holliston6.5 ng/L
  4. Westford4.4 ng/L
  5. Maynard4.2 ng/L
  6. Wayland4 ng/L
4.0 ng/L federal MCL · PFOS, ng/LPFAS in Massachusetts
Lead

0of 24 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 Massachusetts
Who supplies the county

Largest water systems

  1. LowellLOWELL REGIONAL WATER UTILITY · MA3160000
    120,418 served
  2. CambridgeCAMBRIDGE WATER DEPARTMENT · MA3049000
    118,214 served
  3. WalthamWALTHAM WATER DEPARTMENT · MA3308000
    65,218 served
  4. BillericaBILLERICA WATER WORKS · MA3031000
    42,119 served
  5. MarlboroughMARLBOROUGH DPW WATER DIV. (MWRA) · MA2170000
    41,799 served
  6. WoburnWOBURN WATER DEPT. · MA3347000
    40,876 served
  7. NatickNATICK WATER AND SEWER DIVISION · MA3198000
    37,006 served
  8. WatertownWATERTOWN DEPARTMENT OF PUBLIC WORKS · MA3314000
    35,985 served
  9. TewksburyTEWKSBURY WATER DEPARTMENT · MA3295000
    31,342 served
  10. WakefieldWAKEFIELD WATER DEPT · MA3305000
    27,090 served
Questions

Frequently asked

How does Middlesex County tap water compare across cities?

PurityMap ranks 24 cities in Middlesex 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 Marlborough's main water system: MARLBOROUGH DPW WATER DIV. (MWRA) · PWSID MA2170000 · Purity Score 99 (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 Middlesex County cities had a PFAS sample above a 2024 EPA limit?

13 of 24 Middlesex County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Natick (PFOS 37.3 ng/L), Wayland (PFOA 9 ng/L), Westford (PFOA 8.6 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 18.

Is there lead in Middlesex County tap water?

Utilities report lead as a 90th-percentile result from home taps. 22 of 24 Middlesex 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 Middlesex County water systems had drinking-water violations?

3 cities in Middlesex County have 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.

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