Well water in Grafton County, New Hampshire

In Grafton County, 13% of 1,948 private wells tested between 2006 and 2020 had lead above the New Hampshire guidance level (15 ug/L), according to NH DHHS.

2,688 private wells tested 2006 to 2020 in state summaries; 283 individual samples from 222 wells, 1966 to 2025. 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.

An estimated 25,158 people in Grafton County get their drinking water from a private well, per NH DHHS WISDOM, BRFSS 2020. That is about 45% of residents (survey range 38% to 53%).

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. County and state figures combine the town summaries, weighted by wells tested; medians are not combined.

Contaminant	Wells tested	Above state level	Highest	State level
Radon	496	44%	40,701	2,000 pCi/L
Sodium	2,110	23%	1,106	20 mg/L
Iron	2,109	20%	48,600	300 ug/L
Lead (stagnant)	1,948	13%	10,400	15 ug/L
Copper (stagnant)	1,939	13%	58.1	1.3 mg/L
Arsenic	2,176	5%	313	5 ug/L
Manganese	2,113	5%	19,100	300 ug/L
Uranium	2,141	2%	361	30 ug/L
Chloride	2,688	2%	1,800	250 mg/L
Fluoride	2,594	<1%	11	4 mg/L
Nitrate	2,687	<1%	20	10 mg/L
Nitrite	2,686	0%	0.4	1 mg/L

What individual samples found

Each row summarizes every public sample for that contaminant inside Grafton County. 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 1986 to 2022	67	33%	1%	0	30	10 ug/L EPA limit
Lead 1986 to 2022	73	36%	1%	0	20	15 ug/L EPA limit
Nitrate 1966 to 2021	283	48%	<1%	0	11.7	10 mg/L EPA limit
Fluoride 1966 to 2021	240	75%	0%	0.2	3.2	4 mg/L EPA limit
Copper 1987 to 2022	70	39%	0%	0	0.807	1.3 mg/L EPA limit
Radium (226 + 228) 1988 to 2017	36	69%	0%	0	1.2	5 pCi/L EPA limit
Uranium 1995 to 2022	30	73%	0%	0.176	17.3	30 ug/L EPA limit
Chloride 1966 to 2021	246	64%	no limit	2	389	250 mg/L nuisance level
Manganese 1966 to 2022	244	71%	no limit	30	909	300 ug/L health guideline
Sodium 1966 to 2021	214	88%	no limit	7	570	20 mg/L health guideline
Radon 1986 to 2002	29	100%	no limit	1,500	23,300	2,000 pCi/L health guideline
Iron 1986 to 2002	10	90%	no limit	100	5,400	300 ug/L nuisance level

Sampled fewer than 10 times, too few to summarize: PFOA (8), PFHxS (8), PFOS (8), PFNA (8), E. coli (6).

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What this means

Among homeowners in Grafton County who sent a sample to the state lab, the health-based limits most often exceeded were lead (13% of 1,948 wells), copper (13% of 1,939 wells), and arsenic (5% of 2,176 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.

Radon was above the New Hampshire guidance level of 2,000 pCi/L in 44% of 496 wells. Radon in water matters because it moves into indoor air during showers and laundry.

Sodium and iron exceed the state's advisory level in a sizable share of wells; these are mostly a taste, staining or diet issue rather than a toxicity one.

What to test for in Grafton County

Volatile organic compounds (VOCs)205 leaking underground storage tank sites on record locally.
PFAS38 unlined landfills on record locally.
Metals panel50 hazardous waste sites on record locally.
Radon44% of 496 local wells tested were above the New Hampshire guidance level.
Sodium23% of 2,110 local wells tested were above the New Hampshire guidance level.
Iron20% of 2,109 local wells tested were above the New Hampshire guidance level.
Copper13% of 1,939 local wells tested were above the New Hampshire guidance level.
Manganese5% of 2,113 local wells tested were above the New Hampshire guidance level.
Uranium2% of 2,141 local wells tested were above the New Hampshire guidance level.
Chloride2% of 2,688 local wells tested were above the New Hampshire guidance level.
Fluoride<1% of 2,594 local wells tested were above the New Hampshire guidance level.

Wells in Grafton County

8,027 domestic wells in Grafton County are on record with the state since 1980. 98% are drilled into bedrock, and the typical well is 340 feet deep (one in ten goes past 600 feet).

In a typical Grafton County well, bedrock starts about 27 feet down, the median yield is 7 gallons per minute, 22% 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.

1,764

1980s

456

1990s

2,642

2000s

1,663

2010s

1,495

2020s

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 Grafton County

NHDES records 205 leaking underground storage tank sites, 38 unlined landfills, 50 hazardous waste sites, and 113 reported spills and releases in Grafton County, among 2,016 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.

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

Treatment that fits the local profile

Lead: Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching
Copper: Neutralizing filter to raise pH; Point-of-use reverse osmosis
Arsenic: Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Radon: Aeration (bubble-up or diffused) whole-house; Granular activated carbon whole-house (lower levels only)
Sodium: Point-of-use reverse osmosis; Distillation
Nitrate: Point-of-use reverse osmosis; Anion exchange; Distillation

Book a free water test in Grafton County

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 Grafton County?

The typical domestic well in Grafton County is 340 feet deep, based on 8,027 wells reported to the state since 1980. One in ten is deeper than 600 feet. 98% are drilled into bedrock.

Is there arsenic in well water in Grafton County?

Arsenic was detected in 33% of 67 public well samples in Grafton County, and 1% 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 Grafton County?

The median radon level across 29 public samples in Grafton County was 1,500 pCi/L, with a high of 23,300 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Grafton County?

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 in Grafton County

Alexandria21% lead
Ashland13% copper
Bath7% arsenic
Bethlehem27% uranium
Bridgewater15% lead
Bristol15% lead
Campton14% copper
Canaan12% uranium
Enfield15% copper
Franconia14% lead
Grafton20% lead
Groton6% fluoride
Hanover10% lead
Haverhill13% copper
Hebron16% lead
Holderness17% arsenic
Lebanon14% lead
Lisbon0% nitrate
Littleton18% arsenic
Lyme12% lead
Orford9% lead
Piermont20% lead
Plymouth14% lead
Rumney21% copper
Sugar Hill24% lead
Thornton18% lead
Warren24% copper
Wentworth13% copper
Woodstock0% fluoride

11 towns have fewer than 30 public samples and are included in the Grafton County totals above rather than shown separately: Benton, Dorchester, Easton, Ellsworth, Landaff, Lincoln, Livermore, Lyman, Monroe, Orange, Waterville Valley.

Sources

USGS Water Quality Portal: 1,548 samples in Grafton County. 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: 32 samples in Grafton County. 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: summaries for 12 contaminants in Grafton County, up to 2,688 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: 9,159 well records in Grafton County, 8,027 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: 2,016 regulated sites located in Grafton County. 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.