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States → New Hampshire

State profile · EPA SDWIS + UCMR5

New Hampshire Drinking Water Quality

2,453 public water systems serve 1,242,123 people across New Hampshire, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.

2,453
Water systems
155,970
Total violations
90.2%
Systems w/ a violation
45.1%
PFAS detection rate

The verdict

Across New Hampshire, 2,212 of 2,453 water systems (90.2%) carry at least one EPA violation, and 23 of 51 UCMR5-tested systems show PFAS.

155,970
Total EPA violations on record
19%
Health-based (MCL / treatment)
90.2%
Systems with ≥1 violation
45.1%
UCMR5 PFAS detection rate
Water Systems
2,453
Total Violations
155,970
Violation Rate
90.2%
PFAS Detection
45.1%
23 of 51 tested

Violation Composition

How New Hampshire's 155,970 violations break down by type, per EPA SDWIS classification.

Health-based (29,649) Monitoring/Reporting (126,321)
Metric Value Share
Public water systems2,453-
Population served1,242,123-
Total violations155,970100%
Health-based violations29,64919.0%
Systems with violations2,21290.2%
PFAS detection rate23 of 5145.1%

Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.

Largest Water Systems

Manchester Water Works
Manchester, NH · 123,500 served
6 violations
Pennichuck Water Works
Nashua, NH · 89,073 served
5 violations
Concord Water Dept
Concord, NH · 44,215 served
4 violations
Aquarion Water/NH
Monroe, NH · 34,000 served
19 violations
Portsmouth Water Works
Portsmouth, NH · 33,000 served
43 violations
Keene Water Dept
Keene, NH · 30,000 served
81 violations
Dover Water Dept
Dover, NH · 29,000 served
155 violations
Merrimack Village Dist
Merrimack, NH · 25,500 served
170 violations
Rochester Water Dept
Rochester, NH · 25,000 served
43 violations
Laconia Water Works
Lakeport, NH · 21,000 served
Salem Water Dept
Salem, NH · 21,000 served
33 violations
Derry Water Dept
Derry, NH · 17,210 served
12 violations
Hudson Water Dept
Hudson, NH · 16,700 served
10 violations
Unh/Durham Water Sys
Durham, NH · 16,000 served
9 violations
Seabrook Water Dept
Seabrook, NH · 14,000 served
1,029 violations
Exeter Water Dept
Exeter, NH · 12,236 served
268 violations
Somersworth Water Works
Somersworth, NH · 12,000 served
160 violations
Lebanon Water Dept
Lebanon, NH · 10,050 served
10 violations
Pease Trade Port
Portsmouth, NH · 9,900 served
7 violations
Berlin Water Works
Berlin, NH · 9,575 served
11 violations

Most Violations

#1 Seabrook Water Dept Seabrook
1,029
#2 Errol Water Works/West Errol
973
#3 Morningside Drive Derry
934
#4 View Point Coop Swanzey
928
#5 Glencliff Improvement Glencliff
872
#6 Westview Meadows Belmont
866
#7 Pleasant Valley Park Estates Winnisquam
757
#8 Hillsborough Water Works Hillsborough
737
#9 Boumil Grove Condos Andover
706
#10 Orford Village Dist Orford
704
#11 20 Jaffrey RD New Ipswich
694
#12 Gunstock Glen Water Moultonborough
678
#13 Profile Apartments Madbury
669
#14 Hawthorne Village Southboro
630
#15 Wagon Wheel Londonderry
628

Counties in New Hampshire

Hillsborough
280 systems · 336,342 served · 17,880 violations
Rockingham
559 systems · 273,232 served · 32,389 violations
Merrimack
247 systems · 124,101 served · 14,635 violations
Strafford
132 systems · 107,387 served · 8,921 violations
Grafton
269 systems · 101,638 served · 20,540 violations
Carroll
363 systems · 80,560 served · 21,120 violations
Belknap
255 systems · 74,926 served · 16,111 violations
Cheshire
170 systems · 69,097 served · 12,313 violations
Coos
113 systems · 41,156 served · 7,377 violations
Sullivan
65 systems · 33,684 served · 4,684 violations
View all 2,453 systems in New Hampshire →

Drinking Water Guides

Is Your Tap Water Safe?

How to interpret water quality reports and know when to take action.
PFAS in Drinking Water

What forever chemicals are, EPA testing results, and 2024 standards.
Check Your Water System

Step-by-step guide to finding and understanding your local water data.

Frequently Asked Questions

How many water systems are in New Hampshire? ▼
New Hampshire has 2,453 public water systems serving approximately 1,242,123 people. These include community water systems, non-transient non-community systems, and transient non-community systems regulated under the Safe Drinking Water Act.
How many drinking water violations are in New Hampshire? ▼
New Hampshire has 155,970 total drinking water violations on record, with 29,649 classified as health-based violations. 90.2% of water systems in the state have at least one violation.
Has PFAS been found in New Hampshire drinking water? ▼
Of 51 water systems tested for PFAS in New Hampshire, 23 had PFAS detected, a 45.1% detection rate. PFAS are persistent "forever chemicals" that do not break down in the environment.
What is the violation rate for New Hampshire water systems? ▼
New Hampshire's violation rate is 90.2%. This measures the percentage of public water systems that have at least one recorded violation in the EPA SDWIS database, including both health-based and monitoring/reporting violations.
Where does this New Hampshire water data come from? ▼
All drinking water data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS is the federal database that tracks compliance for all public water systems regulated under the Safe Drinking Water Act.

Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Read our methodology - how this data is sourced, computed, and verified.

Related

All states → | Most violations → | Compare counties →
Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

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.