How many water violations are in Middlesex County?

Middlesex County has 16,575 total drinking water violations across 204 water systems, of which 1,068 are health-based violations. 97.5% of systems have at least one violation.

How many people get water from Middlesex County systems?

Water systems in Middlesex County serve approximately 1,623,176 people through 204 public water systems.

Has PFAS been detected in Middlesex County water?

Under EPA UCMR5, 33 of 54 tested systems in Middlesex County had at least one PFAS detection (61.1% of the UCMR5-tested subset - not of all 204 SDWIS systems).

What types of water sources supply Middlesex County?

Water systems in Middlesex County use GW (158 systems), SW (45 systems), Unknown (1 systems) as their primary water sources.

Are health-based violations serious?

Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 6.4% of Middlesex County's violations are health-based. Among counties with any SDWIS violations, this extract puts Middlesex County in the lower health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

Counties → Massachusetts

Middlesex County, Massachusetts

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet MA017 · Middlesex County 204 sys · 16,575 viol · #26/3254

VIOL-SEVERE · HEALTH-LOW · RANK-TOP · PHOTO-FINISH · PFAS-HIGH · SRC-GW · SYS-LARGE · BOOK-FULL

VIOL-SEVERE 97.5% flagged
HEALTH-LOW 6.4% health
RANK-TOP #26/3254
PHOTO-FINISH ±0.2 pp
PFAS-HIGH 61.1% detect
SRC-GW GW lead 77%
SYS-LARGE 204 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Hampden County ( -0.2 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Middlesex County ranks #26 of 3,254 counties by people served, and #2 of 14 counties in Massachusetts. See methodology · corpus placement.

Middlesex County standing, mid-flagged corpus third

Flagged-system rate 97.5% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 6.4% is health-based share at or below the lower third (≤ 10.3%) . UCMR5 detect rate 61.1% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #26 of 3,254 · #2 of 14 in Massachusetts.

Water Systems

System Name	Population	Violations	PFAS
Cambridge Water Department	118,214	70	Detected
Lowell Regional Water Utility	115,000	54	Detected
Newton Water Dept. (Mwra)	88,415	22	Clean
Somerville Water Dept. (Mwra)	81,045	33	Clean
Framingham Water Dept. (Mwra)	72,362	12	Clean
Malden Water Division (Mwra)	66,263	45	Clean
Waltham Water Department	65,218	35	Clean
Medford Water Dept. (Mwra)	61,700	27	Clean
Everett Water Dept. (Mwra)	49,075	23	Clean
Arlington Water Dept. (Mwra)	46,308	21	Clean
Billerica Water Works	42,119	52	Detected
Marlborough Dpw Water Div. (Mwra)	41,799	56	Clean
Woburn Water Dept.	40,876	46	Detected
Natick Water and Sewer Division	37,006	146	Detected
Watertown Water Dept. (Mwra)	35,329	19	Clean
Lexington Water Dept. (Mwra)	34,074	17	Clean
Tewksbury Water Department	31,342	30	Detected
Melrose Water Division (Mwra)	29,357	45	Clean
Chelmsford Water District	28,750	12	Detected
Reading Water Department (Mwra)	27,358	7	Clean
Belmont Water Dept. (Mwra)	27,295	11	Clean
Wakefield Water Dept	27,090	113	Detected
Burlington Water Dept	26,680	278	Detected
Dracut Water Supply District	25,789	114	Detected
Stoneham Water Dept (Mwra Supply)	23,244	33	Clean
Winchester Water Dept	22,970	62	Clean
Wilmington Water Dept	22,481	65	Detected
Acton Water Supply District	20,780	174	Detected
Hudson Water Supply	20,032	285	Detected
Ashland Water and Sewer Dept.	18,832	45	Detected
Concord Water Dept	18,788	25	Detected
Westford Water Department	18,680	28	Detected
Sudbury Water District	18,416	284	Detected
North Reading Water Dept.	16,054	61	Detected
Holliston Water Department	15,713	288	Detected
Bedford Water Dept.	14,394	137	Clean
Wayland Water Department	13,196	101	Detected
Hopkinton Water Department	12,586	23	Detected
Weston Water Dept.	11,941	33	Clean
Hanscom Afb	11,789	41	Clean
Maynard Dpw, Water Division	10,401	304	Detected
Kenwood Water District	9,620	29	Detected
Littleton Water Department	9,611	54	Clean
Pepperell Dpw Water Division	9,217	141	Detected
Ayer Dpw Water Division	8,479	55	Detected
North Chelmsford Water Dist	7,498	14	Clean
Devens Massdevelopment	6,500	49	Detected
Townsend Water Department	6,500	246	Detected
Lincoln Water Dept	5,593	90	Detected
Groton Water Department	5,456	110	Detected

Compare beyond Massachusetts

Mid-flagged peers for Middlesex County

Cross-state counties nearest Middlesex County on flagged-system share (97.5%) and cumulative violation count (16,575). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Compiled by PlainWater, Drinking Water Quality Editorial Process · May 15, 2026

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.