Well water in Portsmouth, New Hampshire

No public well test results have been compiled for Portsmouth yet. The USGS national arsenic model estimates that 45% of the 0 people on private wells there draw water with arsenic above 5 ug/L, the EPA limit, based on geology, well depth and land use rather than local tests.

The strongest signal is coliform bacteria: Recommended for every private well, every year, too few samples to carry the headline but first on the test list below.

44 test results across 13 contaminants from at least 8 wells, 1977 to 2024; iron has the most at 8. Data refreshed September 3, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

NHDES samples private wells near known or suspected PFAS sources (industrial sites, airports, landfills, fire training areas), and wells with a detection are resampled over time. PFAS shares describe wells that were tested for a reason, not every well in the area.

Data confidence: estimate. No state program or federal monitoring data for Portsmouth has been compiled here yet, so the arsenic figure is the USGS national model, not a measurement. Treat a high estimate as a reason to test, not as your well's number. Measured results are added as states publish them.

Closer than the town

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

Among contaminants with a federal limit, no tested sample in Portsmouth came back above it. That is reassuring, but sampling is uneven: wells that were never tested are not in this data.

Chloride is widespread in local groundwater. It is mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Portsmouth

1
Coliform bacteria
Recommended for every private well, every year.
2
Nitrate
Recommended for every private well, especially near farms or septic systems.
3
PFOA
Above the limit in 1 of 2 local samples; too few to quote a rate.
4
Chloride
Detected in 100% of local samples.
5
Fluoride
Detected in 67% of local samples.
6
Volatile organic compounds (VOCs)
88 leaking underground storage tank sites on record locally.
7
PFAS
4 unlined landfills on record locally.
8
Metals panel
23 hazardous waste sites on record locally.

Test your Portsmouth well for coliform bacteria, nitrate and PFOA

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in New Hampshire: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Portsmouth numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Wells in Portsmouth

58 domestic wells in Portsmouth are on record with the state since 1984. 81% are drilled into bedrock, and the typical well is 203 feet deep (one in ten goes past 440 feet).

In a typical Portsmouth well, bedrock starts about 6 feet down, the median yield is 15 gallons per minute, 4% 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.

1980s

1990s

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.

The rock under Portsmouth

Not a principal aquifer

The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the town centroid. A single well can sit in a different unit, especially near a boundary.

Official help in New Hampshire

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Wells, NHDES
New Hampshire Environmental Laboratory Accreditation Program, NHDES

Contamination sources on record in Portsmouth

NHDES records 88 leaking underground storage tank sites, 4 unlined landfills, 23 hazardous waste sites, and 38 reported spills and releases in Portsmouth, among 451 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.

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

Treatment that fits the local profile

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For manganese

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in Portsmouth

No water treatment company serves Portsmouth through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Portsmouth, and you get an email naming it first.

Common questions

How deep are wells in Portsmouth?

The typical domestic well in Portsmouth is 203 feet deep, based on 58 wells reported to the state since 1984. One in ten is deeper than 440 feet. 81% are drilled into bedrock.

How often should I test a private well in Portsmouth?

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.

Towns near Portsmouth

Closest first. Groundwater does not stop at a line on a map, so the next town over is a fair second opinion.

Want the numbers themselves? Download the New Hampshire dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 36 samples in Portsmouth. 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 PFAS sampling: 8 samples in Portsmouth. PFAS results for private wells from the New Hampshire Department of Environmental Services Environmental Monitoring Database. Retrieved September 3, 2026.
NH DHHS WISDOM private well summaries: modeled chance (45%) that a well in Portsmouth exceeds 5 ug/L of arsenic, from geology rather than tests. Town summaries of private well tests run by the New Hampshire Public Health Laboratories, published by NH DHHS through the WISDOM environmental public health tracking portal. Retrieved September 3, 2026.
NHDES Water Well Inventory: 469 well records in Portsmouth, 58 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: 451 regulated sites located in Portsmouth. 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.