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Counties → New Hampshire

Merrimack County, New Hampshire

SDWIS compliance plate

Sheet NH013 · Merrimack County 247 sys · 14,635 viol · #505/3254

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

  • VIOL-SEVERE 92.7% flagged
  • HEALTH-MID 21.5% health
  • RANK-TOP #505/3254
  • PHOTO-FINISH ±1.0 pp
  • PFAS-MID 28.6% detect
  • SRC-GW GW lead 98%
  • SYS-LARGE 247 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Carroll County ( -1 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Merrimack County ranks #505 of 3,254 counties by people served, and #3 of 10 counties in New Hampshire. See methodology · corpus placement.

Merrimack County standing, lower-flagged corpus third

Flagged-system rate 92.7% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 21.5% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 28.6% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #505 of 3,254 · #3 of 10 in New Hampshire.

Flagged-rate neighbourhood around Merrimack County

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

0% 20% 40% 60% 80% 100% Sullivan · lowest Coos · near Merrimack · this county 86.2% 90.9% 91.2% 91.7% 92.7% 94.4%

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

Water Systems

System Name Population Violations PFAS
Concord Water Dept 44,215 4 Clean
Franklin Water Works 7,000 367 Clean
Pembroke Water Works 5,200 146 Detected
Central Hooksett Water Pct 4,650 30 Detected
Penacook Boscawen Water Pct 3,800 50 Clean
Cogswell Springs Water Works 3,000 42 -
Hooksett Village Water Pct 3,000 60 -
New London Springfield Water 2,750 285 Clean
Tilton Northfield Water Dist 2,500 379 -
NH Motor Speedway 2,300 22 -
Pittsfield Aqueduct 1,630 376 -
Contoocook Village Pct 1,600 93 -
Canterbury Rest Area 1,505 12 -
Sutton Rest Area 1,160 0 -
Rapid Refill 135 999 5 -
Wendys/Dunkin Donuts 999 8 -
Mt Sunapee Ski Area/Main Lodge 950 7 -
Mt Sunapee Ski Area/Summit 950 16 -
Bear View Crossing 800 25 -
Epsom Village Water Distict 800 10 -
McDonalds Restaurant 700 12 -
Warner Village Water Dist 660 61 -
Andover Village Dist 650 264 -
Kearsarge Regional High Sch 650 16 -
Bow High School 645 40 -
Bow Memorial School 615 110 -
Allenstown Community School 608 0 -
Ragged Mountain Ski/Golf 600 48 -
Dunkin Donuts 600 9 -
Kearsarge Regional Middle Sch 550 24 -
Camp Kenwood and Evergreen 534 28 -
Bow Elementary School 522 145 -
Chucksters 500 0 -
Elm Brook Park 500 8 -
Dunkin Donuts 500 19 -
Mt Sunapee State Pk/Bath House 500 10 -
Cascade Campground/Lower 475 97 -
Sandy Beach RV Resort I 463 37 -
Spacious Skies French Pond 400 43 -
Circle 9 Ranch Campground 395 115 -
Catamount Hill 383 94 -
Cozy Pond Camping Resort/West 375 60 -
Freedom Hill/Pine Ridge Est 370 190 -
Kings Towne MHP 350 63 -
Hill Water Works 350 60 -
Loudon Elementary Sch 321 7 -
Pitco Frialator 311 20 -
Chen Yang Li Restaurant 300 138 -
Chucksters 300 28 -
Shaker RD Sch & Childcare Ctr 300 14 -

Compare beyond New Hampshire

Lower-flagged peers for Merrimack County

Cross-state counties nearest Merrimack County on flagged-system share (92.7%) and cumulative violation count (14,635). 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.