Well water in Seabrook, New Hampshire

In Seabrook, 48% of 93 tested private well samples exceeded the EPA limit for arsenic (10 ug/L), based on public data from USGS Water Quality Portal.

94 individual samples from 3 wells, 1987 to 2019. Data refreshed September 3, 2026.

Separately, a USGS and NHDES statistical model puts the chance that a bedrock well in Seabrook exceeds 5 ug/L of arsenic at 60% (as low as 39% in parts of town), based on geology rather than tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Seabrook. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Samples	Detected	Above limit	Median	Highest	Limit
Arsenic 1987 to 2019	93	99%	48%	4.6	23.7	10 ug/L EPA limit
Fluoride 1987 to 2019	93	98%	0%	0.07	0.1	4 mg/L EPA limit
Nitrate 2014 to 2019	88	51%	0%	0.068	2.66	10 mg/L EPA limit
Uranium 2014 to 2019	48	98%	0%	2.62	3.4	30 ug/L EPA limit
Lead 1987 to 2019	16	6%	0%	0	0.195	15 ug/L EPA limit
Copper 1987 to 2019	16	44%	0%	0	0.002	1.3 mg/L EPA limit
Manganese 1987 to 2019	94	100%	no limit	115	175	300 ug/L health guideline
Sodium 1987 to 2019	93	100%	no limit	38.7	45.7	20 mg/L health guideline
Chloride 1987 to 2019	93	100%	no limit	49.9	105	250 mg/L nuisance level

Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (4), PFOA (2), PFOS (2), E. coli (1), Iron (6), Radon (2).

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What this means

The contaminants most often above their limit here are arsenic (48% of 93 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Manganese, Chloride, and Iron are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Seabrook

Volatile organic compounds (VOCs)11 leaking underground storage tank sites on record locally.
PFAS1 unlined landfill on record locally.
Metals panel7 hazardous waste sites on record locally.
Arsenic48% of 93 local samples were above the limit.
Coliform bacteriaRecommended for every private well, every year.
RadonMedian local reading is 1,225 pCi/L.
ManganeseDetected in 100% of local samples.
ChlorideDetected in 100% of local samples.
IronDetected in 100% of local samples.
NitrateRecommended for every private well, especially near farms or septic systems.

Wells in Seabrook

60 domestic wells in Seabrook are on record with the state since 1999. 92% are drilled into bedrock, and the typical well is 230 feet deep (one in ten goes past 507 feet).

In a typical Seabrook well, bedrock starts about 35 feet down, the median yield is 16 gallons per minute, 11% of wells yield under 3 gallons per minute and usually need a storage tank.

Bedrock wells are where arsenic, uranium and radon come from: the water sits in fractures in granite and metamorphic rock and picks up whatever the rock carries. That is why testing for those three matters more here than in a dug or gravel well.

2000s

2010s

Find your own well's report

The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.

Open NHDES OneStop and choose Water Well.
Enter your town and one word of your street name. Leave out the house number and the Road or Street part; a short search matches more.
In the results, click Show for your address to see the report: total depth, depth to bedrock, casing, yield in gallons per minute, static water level, and the driller.
Save Results exports the whole list to a spreadsheet.

Reports exist only for wells drilled since January 1984, when reporting became mandatory, and street names are as they were when the well was drilled.

Contamination sources on record in Seabrook

NHDES records 11 leaking underground storage tank sites, 1 unlined landfill, 7 hazardous waste sites, and 12 reported spills and releases in Seabrook, among 187 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

11: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
1: unlined landfillOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
7: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
12: reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
24: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
59: locally identified potential contamination sourcesTowns inventory these (vehicle repair, labs, salt piles, farms) when they draw wellhead protection maps.
71: other remediation projects
2: other solid waste facilities

Treatment that fits the local profile

Arsenic: Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Fluoride: Point-of-use reverse osmosis; Activated alumina; Distillation
Manganese: Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Chloride: Point-of-use reverse osmosis; Distillation
Iron: Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

Book a free water test in Seabrook

A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation.

Common questions

How deep are wells in Seabrook?

The typical domestic well in Seabrook is 230 feet deep, based on 60 wells reported to the state since 1999. One in ten is deeper than 507 feet. 92% are drilled into bedrock.

Is there arsenic in well water in Seabrook?

Arsenic was detected in 99% of 93 public well samples in Seabrook, and 48% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in Seabrook?

The median radon level across 2 public samples in Seabrook was 1,225 pCi/L, with a high of 1,710 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Seabrook?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Sources

USGS Water Quality Portal: 651 samples in Seabrook. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
NHDES Water Well Inventory: 174 well records in Seabrook, 60 domestic. Well construction records reported to the New Hampshire Department of Environmental Services Water Well Board. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 3, 2026.
NHDES OneStop regulated sites: 187 regulated sites located in Seabrook. Remediation sites, underground storage tanks, solid waste facilities and potential contamination sources from the New Hampshire Department of Environmental Services OneStop database. Retrieved September 3, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.