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Counties → Maryland

Montgomery County, Maryland

SDWIS compliance plate

Sheet MD031 · Montgomery County 56 sys · 1,796 viol · #20/3254

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

  • VIOL-SEVERE 87.5% flagged
  • HEALTH-MID 27.6% health
  • RANK-TOP #20/3254
  • PHOTO-FINISH ±0.7 pp
  • PFAS-HIGH 100.0% detect
  • SRC-GW GW lead 84%
  • SYS-MID 56 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Harford County (+ 0.7 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Montgomery County ranks #20 of 3,254 counties by people served, and #1 of 24 counties in Maryland. See methodology · corpus placement.

Montgomery County standing, lower-flagged corpus third

Flagged-system rate 87.5% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 27.6% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 100.0% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #20 of 3,254 · #1 of 24 in Maryland.

Flagged-rate neighbourhood around Montgomery County

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

0% 20% 40% 60% 80% 100% Baltimore city · lowest Washington · near Montgomery · this county Kent · highest 38.5% 83.8% 85.4% 85.4% 87.5% 88.2% 96.6%

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

Water Systems

System Name Population Violations PFAS
Washington Suburban Sanitary Commission 1,900,000 2 Detected
City of Rockville 52,000 220 Detected
Town of Poolesville 6,005 144 Detected
Adventist Healthcare Shady Grove Med Ctr 2,100 0 -
Suburban Hospital 1,900 0 -
Fairland Crossing Apartments 1,248 0 -
National Institutes of Health 1,100 0 -
Glenstone Foundation 537 6 -
Dickerson Market 510 17 -
Darnestown Swim and Raquet Club 470 13 -
The Barnesville School 440 59 -
Smokey Glen Farm - Picnic Pavillion 400 17 -
Smokey Glen Farm- Grove Area 400 2 -
Monocacy Elementary School 351 41 -
Whitley Park Condominiums 256 0 -
Comus Inn 256 12 -
Montgomery Country Club 200 11 -
Old Anglers Inn 200 5 -
Laytonsville Golf Course- Clubhouse 200 31 -
Little Bennett Golf Course-Clubhouse 200 19 -
Boyds Presb and Elf School,camp Sunshine 180 13 -
Brooke Grove Retirement Village 170 0 -
Butler School 169 68 -
Mater Amoris Montessori School 155 31 -
N.i.h. Animal Center 150 25 -
T.w. Enterprize and Texs Carryout 138 40 -
Glenvilah Center I [12944 A-E] 138 24 -
Ruppert Landscape 119 21 -
Whites Ferry Store 115 25 -
Empire Cafe 105 16 -
Bretton Woods Recreation Center 100 11 -
Potomac Swim and Tennis 100 29 -
Sunshine General Store 100 115 -
Tri-County Baptist Church 100 13 -
Glenvilah Center II [12948 A-F] 93 101 -
Camp Bennett Lodge [Union Mission] 80 28 -
Cedar Grove Beer and Wine 80 16 -
Etchison Country Store 80 32 -
Camp Bennett Office/[Union Mission] 80 2 -
Pleasants Excavation Co., Inc. 75 92 -
New Hope Presbyterian/Clc Preschool 71 17 -
Denise Bakery 70 42 -
Montgomery Co Resource Recovery Facility 64 7 -
Seneca Academy & the Circle School 60 25 -
C.s.a.a.c. - Brookeville School Campus 60 14 -
Glenvilah Center III [12960- 12964] 50 16 -
St. Marys Church 50 1 -
Little Bennett- Driving Range 50 24 -
Poolesville Public Golf Club 40 26 -
Dayspring Church - Wellspring Well 37 0 -

Compare beyond Maryland

Lower-flagged peers for Montgomery County

Cross-state counties nearest Montgomery County on flagged-system share (87.5%) and cumulative violation count (1,796). 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.