Well water in Madbury, New Hampshire
In Madbury, 42% of 45 private wells tested between 2006 and 2020 had arsenic above the New Hampshire guidance level (5 ug/L), according to NH DHHS.
49 private wells tested 2006 to 2020 in state summaries; 88 individual samples from 84 wells, 1952 to 2026. Data refreshed September 3, 2026.
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. In that targeted sampling, 14% of 88 PFOA results in Madbury were above the EPA limit of 4 ng/L. In that targeted sampling, 5% of 88 PFOS results in Madbury were above the EPA limit of 4 ng/L.
Separately, a USGS and NHDES statistical model puts the chance that a bedrock well in Madbury exceeds 5 ug/L of arsenic at 61% (as low as 34% in parts of town), based on geology rather than tests.
What homeowner tests found
NH DHHS WISDOM private well summaries: private wells tested and reported to the state, 2006 to 2020. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA.
What individual samples found
Each row summarizes every public sample for that contaminant inside Madbury. 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 | |
|---|---|---|---|---|---|---|---|
| PFOA 2022 to 2026 | 88 | 68% | 14% | 0.74 | 19 | 4 ng/L EPA limit | |
| PFOS 2022 to 2026 | 88 | 45% | 5% | 0 | 20 | 4 ng/L EPA limit | |
| PFHxS 2022 to 2026 | 88 | 61% | 1% | 0.225 | 11 | 10 ng/L EPA limit | |
| PFNA 2022 to 2026 | 88 | 11% | 0% | 0 | 1.5 | 10 ng/L EPA limit |
Sampled fewer than 10 times, too few to summarize: Arsenic (4), Nitrate (6), Fluoride (5), Copper (2), Lead (2), Chloride (8), Manganese (5), Sodium (5), Radon (2).
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What this means
Among homeowners in Madbury who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (42% of 45 wells) and nitrate (2% of 49 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.
Sodium exceeds the state's advisory level in a sizable share of wells; this is mostly a taste, staining or diet issue rather than a toxicity one.
What to test for in Madbury
- Volatile organic compounds (VOCs)1 leaking underground storage tank site on record locally.
- PFAS2 unlined landfills on record locally.
- Metals panel1 hazardous waste site on record locally.
- Sodium49% of 45 local wells tested were above the New Hampshire guidance level.
- Arsenic42% of 45 local wells tested were above the New Hampshire guidance level.
- PFOA14% of 88 local samples were above the limit.
- Iron9% of 44 local wells tested were above the New Hampshire guidance level.
- PFOS5% of 88 local samples were above the limit.
- Manganese2% of 44 local wells tested were above the New Hampshire guidance level.
- Nitrate2% of 49 local wells tested were above the New Hampshire guidance level.
- PFHxS1% of 88 local samples were above the limit.
Wells in Madbury
255 domestic wells in Madbury are on record with the state since 1983. 100% are drilled into bedrock, and the typical well is 340 feet deep (one in ten goes past 584 feet).
In a typical Madbury well, bedrock starts about 15 feet down, the median yield is 9 gallons per minute, 13% 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.
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 Madbury
NHDES records 1 leaking underground storage tank site, 2 unlined landfills, 1 hazardous waste site, and 5 reported spills and releases in Madbury, among 43 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.
- 1
- leaking underground storage tank siteGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 2
- unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 1
- hazardous waste siteSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 5
- reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
- 3
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 9
- locally identified potential contamination sourcesTowns inventory these (vehicle repair, labs, salt piles, farms) when they draw wellhead protection maps.
- 20
- 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
- Sodium
- Point-of-use reverse osmosis; Distillation
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- PFOA
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- PFOS
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- PFHxS
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
Book a free water test in Madbury
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 Madbury?
The typical domestic well in Madbury is 340 feet deep, based on 255 wells reported to the state since 1983. One in ten is deeper than 584 feet. 100% are drilled into bedrock.
Is there arsenic in well water in Madbury?
Arsenic was detected in 50% of 4 public well samples in Madbury, and 25% 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 Madbury?
The median radon level across 2 public samples in Madbury was 1,300 pCi/L, with a high of 1,500 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Madbury?
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
- NHDES PFAS sampling: 352 samples in Madbury. PFAS results for private wells from the New Hampshire Department of Environmental Services Environmental Monitoring Database. Retrieved September 3, 2026.
- USGS Water Quality Portal: 39 samples in Madbury. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- NH DHHS WISDOM private well summaries: summaries for 8 contaminants in Madbury, up to 49 wells each. 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. Exceedance shares use New Hampshire guidance levels, which are stricter than EPA for arsenic (5 ug/L), manganese (0.3 mg/L), radon (2,000 pCi/L) and sodium (20 mg/L). Statistics for small counts are suppressed (*). Retrieved September 3, 2026.
- NHDES Water Well Inventory: 301 well records in Madbury, 255 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: 43 regulated sites located in Madbury. 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.