Well water in Nantucket County, Massachusetts
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Testing strongly recommended
private wells tested between 2020 and 2023 in Nantucket County had PFOA above the EPA limit (4 ng/L), according to MassDEP.
48 private wells tested 2020 to 2023 in state summaries; 106 test results across 9 contaminants from at least 15 wells, 1976 to 1977; nitrate has the most at 24. Data refreshed September 16, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
MassDEP offered free PFAS tests to towns without public water and to wells near suspected sources such as landfills, fire stations and airports, so these shares describe the wells that took part rather than every well in town.
An estimated 2,625 people in Nantucket County get their drinking water from a private well, per USGS 2015 county water use. That is about 24% of residents.
Separately, the USGS national arsenic model estimates that 0% of the 2,625 people on private wells in Nantucket County draw water above 10 ug/L, from geology and well depth rather than local tests.
What homeowner tests found
MassDEP Private Well PFAS Sampling Program: private wells tested and reported to the state, 2020 to 2023. 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.
What individual samples found
Each row summarizes every public sample for that contaminant inside Nantucket 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 | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Nitrate 1976 | 24 | 100% | 0.15 | 12 | 10 mg/L EPA limit | |
| Fluoride 1976 | 12 | 75% | 0.1 | 0.2 | 4 mg/L EPA limit | |
| Chloride 1976 to 1977 | no limit | 17 | 100% | 23 | 1,200 | 250 mg/L nuisance level |
| Sodium 1976 to 1977 | no limit | 16 | 100% | 15 | 840 | 20 mg/L health guideline |
| Iron 1976 to 1977 | no limit | 16 | 100% | 280 | 12,000 | 300 ug/L nuisance level |
| Manganese 1976 | no limit | 12 | 33% | 0 | 680 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: Arsenic (3), Copper (3), Lead (3).
Closer than the county
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 addressWhat this means
Among homeowners in Nantucket County who sent a sample to the state lab, the health-based limits most often exceeded were PFOA (23% of 48 wells), PFOS (17% of 48 wells), and PFHxS (4% of 48 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.
What to test for in Nantucket County
- 1PFOA23% of 48 local wells tested were above the EPA limit.
- 2PFOS17% of 48 local wells tested were above the EPA limit.
- 3PFHxS4% of 48 local wells tested were above the EPA limit.
- 4Nitrate4% of 24 local samples were above the limit.
- 5Coliform bacteriaRecommended for every private well, every year.
- 6ChlorideDetected in 100% of local samples.
- 7IronDetected in 100% of local samples.
- 8FluorideDetected in 75% of local samples.
- 9PFAS1 unlined landfill on record locally.
- 10Volatile organic compounds (VOCs)1 unlined landfill on record locally.
- 11Metals panel2 hazardous waste sites on record locally.
Test your Nantucket County well for PFOA, PFOS and PFHxS
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.
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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.
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Where to get a well tested in Massachusetts: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Nantucket County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Nantucket County
2,612 domestic wells in Nantucket County are on record with the state since 1915. <1% are drilled into bedrock, and the typical well is 63 feet deep (one in ten goes past 88 feet).
In a typical Nantucket County well, bedrock starts about 8 feet down, the median yield is 20 gallons per minute, <1% of wells yield under 3 gallons per minute and usually need a storage tank.
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 MassDEP Well Location Viewer and choose Water Well.
- The completion report lists total depth, depth to bedrock, static water level, yield and the driller.
Drillers have filed completion reports with the state since 1984; the viewer's public copy is refreshed a few times a year.
Official help in Massachusetts
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, MassDEP
- Certified Laboratories, MassDEP
Contamination sources on record in Nantucket County
MassDEP records 1 unlined landfill and 2 hazardous waste sites in Nantucket County, among 14 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
- unlined landfillOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
- 2
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 7
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 1
- lined landfill or transfer facility
- 3
- other remediation projects
Treatment that fits the local profile
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
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Chloride
Point-of-use reverse osmosis; Distillation
Iron
Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
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 PFOA
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For PFOA
Whole-house PFAS carbon system
whole-house, at the point of entry, about $3,000
Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.
For PFOA
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
For PFOS
Aquasana Claryum 3-Stage under-sink filter
under-sink or countertop, about $175
Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.
For PFOS
Aquasana HealthShield whole-house filter
whole-house, at the point of entry, about $2,099
Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.
For iron
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
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Common questions
How deep are wells in Nantucket County?
The typical domestic well in Nantucket County is 63 feet deep, based on 2,612 wells reported to the state since 1915. One in ten is deeper than 88 feet. <1% are drilled into bedrock.
How often should I test a private well in Nantucket 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 Nantucket County
Counties near Nantucket County
Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.
Want the numbers themselves? Download the Massachusetts dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 106 samples in Nantucket 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.
- MassDEP Private Well PFAS Sampling Program: summaries for 4 contaminants in Nantucket County, up to 48 wells each. Private well PFAS results from the Massachusetts Department of Environmental Protection free sampling program, 2020 to 2023, one anonymized row per well. Shares are against the EPA limit for each compound (4 ng/L for PFOA and PFOS, 10 ng/L for PFHxS and PFNA). Massachusetts applies its own PFAS6 standard of 20 ng/L to the sum of six compounds; that sum is not a contaminant page here. Zero means not detected. Retrieved September 16, 2026.
- USGS national arsenic model (Ayotte 2017): estimated share of 2,625 people on private wells in Nantucket County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
- MassDEP well completion reports: 2,857 well records in Nantucket County, 2,612 domestic. Well completion reports filed with the Massachusetts Department of Environmental Protection, as published in the Well Location Viewer (April 2023 vintage). Only aggregates are shown; owner names and addresses are never stored. Retrieved September 16, 2026.
- MassDEP regulated sites: 14 regulated sites located in Nantucket County. Chapter 21E release sites, solid waste landfills and underground storage tank facilities from the Massachusetts Department of Environmental Protection, through MassGIS. Retrieved September 16, 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.