Manganese is widespread in Plymouth County wells.
1 widespread, 5 rare out of 6 health checks.
From 19 wells tested in Plymouth County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: radon (5).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 9 people 58,178 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how Plymouth County compares with Massachusetts and the counties around it.
Each result puts Plymouth County next to the 4 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Plymouth County wells.
Manganese5 of 19 wells over
Too few tested to show: Bristol, Norfolk, Suffolk.
These 5 are rare in Plymouth County.
Nitrate0 of 19 wells over
Too few tested to show: Bristol, Norfolk, Suffolk.
Arsenic0 of 19 wells over
Too few tested to show: Bristol, Norfolk, Suffolk.
Uranium0 of 19 wells over
Too few tested to show: Bristol, Norfolk, Suffolk.
Lead0 of 18 wells over
Too few tested to show: Bristol, Norfolk, Suffolk.
Fluoride0 of 19 wells over
Too few tested to show: Bristol, Norfolk, Suffolk.
Too few Plymouth County wells were tested for this one.
Radon in water5 wells tested
None of the 4 Plymouth County wells tested for bacteria had it, but every well needs a yearly test.
Coliform bacteria0 of 4 wells had it
E. coli0 of 4 wells had it
E. coli means human or animal waste is getting in, so if a test of your Plymouth County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 6 of 19 tested wells, and it isn't a health risk.
Iron stains6 of 19 wells had it
Too few tested to show: Bristol, Norfolk, Suffolk.
Plymouth County has 19 tested wells, and the busiest decade for testing was the 2010s.
None of the 19 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Plymouth County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in Plymouth County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Massachusetts offers well owners
- Free testingWe didn't find a free program for all of Massachusetts. Massachusetts's private well page
- Certified labsMassachusetts's list of certified labs
- Well recordsMassachusetts's well record search
Half the household wells here are shallower than 185 feet.
That comes from 5,338 household wells in Massachusetts's drilling records. Most wells of every kind here are 57 to 325 feet deep. Wells as deep as Plymouth County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here are shallower than in 10 of the 13 other Massachusetts counties with enough drilling records.
Look up your own well's depth in Massachusetts's well record search, or see how to find it.
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Plymouth County.
Plymouth County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Between 2023 and 2025 the EPA had 24 town water systems in Plymouth County test for PFAS. 14 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 35 ng/L of PFOS. Only 11 wells in Plymouth County have public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Plymouth County
Is well water in Plymouth County safe to drink?
5 of 19 wells tested in Plymouth County had manganese over the limit, about 1 in 4. Across Massachusetts it's about 2 in 10. That's a bigger share than in 3 of the 4 other Massachusetts counties with 10 or more tested wells. So test your own well for manganese before you count on it.
Where can I get my well tested in Plymouth County?
Use a lab Massachusetts has certified for drinking water. Massachusetts's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Plymouth County.
How deep are wells in Plymouth County?
Half the household wells here are shallower than 185 feet. Typical household wells here are shallower than in 10 of the 13 other Massachusetts counties with enough drilling records.
How does Plymouth County compare with the counties around it?
For manganese, the share of tested wells over the limit: Barnstable, the one neighbor with data, came in lower than Plymouth County, at 21% against 26%. Groundwater doesn't stop at county lines, so Barnstable's 21% is worth knowing about if you live near it.
How often should I test my well in Plymouth County?
None of the 4 wells tested for bacteria in Plymouth County had it, but the CDC still says to test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Plymouth County numbers come from
- People on wells: 58,178 in Plymouth County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 382 well water samples from 19 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2019.
- Well depths: 5,338 Massachusetts drilling records for Plymouth County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 4 counties that share a border with Plymouth County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 24 town water systems in Plymouth County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Plymouth County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Massachusetts Department of Environmental Protection (MassDEP), checked November 1, 2026.