Merrimack County, New Hampshire
32 ZIP codes · Avg score 63/100 · Grade C · Updated 2026-07-19
ZipCheckup grade for Merrimack: C.
A mixed picture - some signals here are worth your attention.
Across Merrimack County's 32 ZIP codes, water safety results are uneven - a portion of systems carry active or recent violations, while others meet standards without issues.
How Merrimack County Compares
How Merrimack County Compares
Merrimack County scores 1 points below the New Hampshire state average (64/100) and 5 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-07-19
ZIP Code Risk Map
Water Quality Map: Merrimack County, New Hampshire
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 11.9 (asthma 11%, diabetes 9.2%)
Estimated additional annual cost per homeowner: $1,653, driven primarily by flood
Infrastructure: 0.484% avg pipe failure probability, 74% of ZIPs at high risk
64.1% of homes built before 1978 (lead paint era)
Violation History (2021–2025)
↑ Worsening trendEPA violation counts by year across Merrimack County water systems. Health-based shown in red, total in blue.
Peak year: 2025 with 43 violations. Past 5 years: 113 total (113 health-based). Health-based violations are rising versus the prior 2-year window - worth closer monitoring.
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $1,653
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
66,383 housing units in Merrimack County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Merrimack County
Remediation costs are relatively manageable for most homeowners in Merrimack County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Merrimack County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water systems serving Merrimack County
8 community water systems serving Merrimack County.
- B
- D
- C
- B
- D
- D
Show all 8 water systems
- B
- D
55 total water systems serve Merrimack County.
Systems with the most violations in Merrimack County
5 water systems with recorded EPA violations.
- D
- D
- D
- B
- D
All ZIP Codes in Merrimack County
32 ZIP codes tracked in Merrimack County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 03235 | Franklin | 83 | B | 0 | $245K |
| 2 | 03106 | Hooksett | 78 | B | 0 | $372K |
| 3 | 03257 | New London | 75 | B | 0 | $469K |
| 4 | 03263 | Pittsfield | 75 | B | 0 | $271K |
| 5 | 03034 | Candia | 74 | B | 2 | $395K |
| 6 | 03278 | Warner | 74 | B | 3 | $323K |
| 7 | 03224 | Canterbury | 72 | B | 0 | $410K |
| 8 | 03229 | Contoocook | 72 | B | 9 (3 health) | $441K |
| 9 | 03243 | Hill | 72 | B | 0 | $243K |
| 10 | 03287 | Wilmot | 72 | B | 0 | $373K |
| 11 | 03304 | Bow | 71 | B | 10 (4 health) | $444K |
| 12 | 03234 | Epsom | 65 | C | 5 (5 health) | $298K |
| 13 | 03275 | Suncook | 64 | C | 4 (1 health) | $309K |
| 14 | 03046 | Dunbarton | 63 | C | 0 | $437K |
| 15 | 03230 | Danbury | 63 | C | 0 | $213K |
| 16 | 03268 | Salisbury | 63 | C | 0 | $313K |
| 17 | 03273 | South Sutton | 63 | C | 0 | $277K |
| 18 | 03280 | Washington | 63 | C | 0 | $288K |
| 19 | 03258 | Chichester | 58 | C | 0 | $360K |
| 20 | 03302 | Concord | 58 | C | 21 (14 health) | — |
| 21 | 03255 | Newbury | 57 | C | 2 | $441K |
| 22 | 03242 | Henniker | 54 | D | 1 (1 health) | $318K |
| 23 | 03221 | Bradford | 53 | D | 0 | $302K |
| 24 | 03231 | East Andover | 53 | D | 0 | — |
| 25 | 03233 | Elkins | 53 | D | 0 | $397K |
| 26 | 03260 | North Sutton | 53 | D | 0 | $297K |
| 27 | 03272 | South Newbury | 53 | D | 0 | — |
| 28 | 03301 | Concord | 53 | D | 21 (14 health) | $344K |
| 29 | 03303 | Concord | 53 | D | 21 (14 health) | $274K |
| 30 | 03216 | Andover | 51 | D | 15 (9 health) | $332K |
| 31 | 03305 | Concord | 50 | D | 21 (14 health) | — |
| 32 | 03307 | Loudon | 40 | D | 11 (8 health) | $316K |
Recommended Buyer Guides for Merrimack County
Below: editorial picks, no sponsored placements.
- Best Water Filters for Lead — Lead above EPA action level in 4 ZIP codes
- Best Lead Paint Test Kits — 64.1% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for Merrimack County, New Hampshire
Overview
Merrimack County in New Hampshire covers 32 ZIP codes with an average Home Safety Score of C (63/100).
14 of 32 ZIP codes have recorded EPA violations. 87 health-based violations have been documented.
← Back to New Hampshire water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.