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Counties → Massachusetts

Barnstable County, Massachusetts

SDWIS compliance plate

Sheet MA001 · Barnstable County 127 sys · 2,953 viol · #110/3254

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

  • VIOL-SEVERE 99.2% flagged
  • HEALTH-LOW 10.3% health
  • RANK-TOP #110/3254
  • PHOTO-FINISH ±0.8 pp
  • PFAS-MID 40.0% detect
  • SRC-GW GW lead 99%
  • SYS-LARGE 127 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Nantucket County (+ 0.8 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Barnstable County ranks #110 of 3,254 counties by people served, and #7 of 14 counties in Massachusetts. See methodology · corpus placement.

Barnstable County standing, mid-flagged corpus third

Flagged-system rate 99.2% is in the corpus middle third (≤ 100.0% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 10.3% is health-based share at or below the lower third (≤ 10.3%) . UCMR5 detect rate 40.0% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #110 of 3,254 · #7 of 14 in Massachusetts.

Flagged-rate neighbourhood around Barnstable County

Lowest/highest poles plus in-state counties nearest Barnstable County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.

0% 20% 40% 60% 80% 100% Suffolk · lowest Middlesex · near Barnstable · this county 87.5% 97.4% 97.5% 97.8% 99.2% 100%

Source: EPA SDWIS (county aggregates) As of 2026-05-15

Water Systems

System Name Population Violations PFAS
Falmouth Water Dept 97,551 59 Clean
Dennis Water District 65,000 44 Detected
Upper Cape Regional Water Cooperative 56,250 23 Clean
Centerville Osterville Marstons Mills WD 50,000 61 Detected
Harwich Water Department 39,144 6 Clean
Yarmouth Water Department 38,900 54 Detected
Mashpee Water District 36,922 8 Detected
Hyannis Water System, Town of Barnstable 35,000 87 Detected
Brewster Water Department 35,000 29 Clean
Chatham Water Department 30,000 85 Clean
Sandwich Water District 23,000 22 Clean
Bourne Water District 22,500 39 Detected
Provincetown Water Department 22,250 29 Clean
Orleans Water Department 18,921 40 Clean
Buzzards Bay Water District 7,700 24 Clean
Town of Eastham 6,199 1 Clean
Otis Air National Guard Base 6,000 28 Clean
Barnstable Fire District 5,400 26 Detected
Cotuit Fire District Water Department 4,938 33 Clean
North Sagamore Water District 4,668 21 Detected
Camp Favorite 1,250 26 -
Sweetwater Forest Inc 1,000 37 -
4100 Holdings LLC 750 21 -
Wellfleet Municipal Water System 750 27 -
Adventure Bound Camping, Cape Cod 660 13 -
Peters Pond Park 633 19 -
Barnstable County Jail 600 15 -
Maurices Campground Inc 600 3 -
Amari Bar and Ristorante 500 22 -
Spring Brook Center, Inc. 500 3 -
Wellfleet Commerce Center, LLC 500 19 -
Ccns Marconi Area 499 85 -
Ccns Coast Guard Station 495 29 -
Ccns Nauset Light Beach 495 15 -
Ccns Highland Area (Truro) 495 11 -
Ccns Truro Pilgrim Heights 490 8 -
YMCA Camp Lyndon 450 26 -
Adventure Bound Camping, Cc @ Hortons 438 2 -
North of Highland Camping Area, LLC 415 10 -
Chequessett Yacht Country Club 350 4 -
Ccns Doane Rock Picnic Area 320 9 -
Sandy Neck Beach 300 11 -
The Wellfleet Beachcomber 300 5 -
Blackfish Variety 300 17 -
Newcomb Hollow Beach 300 3 -
White Crest Beach 300 3 -
Maguire Landing Beach 300 3 -
Gull Pond Beach 300 2 -
Old Village Store 250 15 -
Sheraton Four Points 250 9 -

Compare beyond Massachusetts

Mid-flagged peers for Barnstable County

Cross-state counties nearest Barnstable County on flagged-system share (99.2%) and cumulative violation count (2,953). 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

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.