State Hub
New Hampshire Water Quality
131
Utilities in database
0.8M
Residents served
55%
On private wells
2
Key contaminants tracked
Drinking Water in New Hampshire
New Hampshire has 131 community water systems serving approximately 0.8 million residents. Primary water sources include groundwater. The most commonly reported contaminants include disinfection byproducts, nitrates. 55% of New Hampshire residents rely on private wells. DES holds primary enforcement authority under the Safe Drinking Water Act.
Utilities in New Hampshire
1–25 of 131Manchester Water Works
NH1471010 · 123,500 served
Pennichuck Water Works
NH1621010 · 89,073 served
Concord Water Dept
NH0501010 · 44,215 served
Portsmouth Water Works
NH1951010 · 33,000 served
Keene Water Dept
NH1241010 · 30,000 served
Dover Water Dept
NH0651010 · 29,000 served
Merrimack Village Dist
NH1531010 · 25,500 served
Rochester Water Dept
NH2001010 · 25,000 served
Salem Water Dept
NH2051010 · 21,000 served
Aquarion Water/nh
NH1051010 · 18,950 served
Derry Water Dept
NH0611010 · 17,290 served
Laconia Water Works
NH1281010 · 17,000 served
Hudson Water Dept
NH1201010 · 16,700 served
Unh/durham Water Sys
NH0691010 · 16,000 served
Seabrook Water Dept
NH2111010 · 14,000 served
Lebanon Water Dept
NH1321010 · 13,600 served
Exeter Water Dept
NH0801010 · 12,236 served
Somersworth Water Works
NH2151010 · 12,000 served
Pease Trade Port
NH1951020 · 9,900 served
Hanover Water Dept
NH1071010 · 9,600 served
Berlin Water Works
NH0231010 · 9,575 served
Milford Water Utilities Dept
NH1561010 · 9,500 served
Claremont Water Dept
NH0461010 · 9,000 served
Franklin Water Works
NH0851010 · 7,200 served
Hampstead Area Water
NH1031010 · 7,153 served
Key Contaminant Concerns in New Hampshire
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always from human activity — nitrate interferes with the blood's ability to carry oxygen. The United States produces over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination.
DBPs
When utilities add chlorine to water to kill pathogens, it reacts with dissolved organic matter — leaves, algae, soil — to produce disinfection byproducts (DBPs). Over 600 DBPs have been identified. The EPA regulates two groups: total trihalomethanes (TTHMs, including chloroform) and haloacetic acids (HAA5). DBP levels tend to be highest in surface water systems and in warm months when organic matter is elevated.
New Hampshire Water FAQs
Quick Links
Data source: Utility data from EPA SDWIS. 131 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-22