Arsenic is widespread in Worcester County wells.
1 widespread, 1 worth checking, 3 rare out of 5 health checks.
From 64 wells tested in Worcester County since 2002; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: nitrate (4), radon (2).
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 5 people 160,468 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)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how Worcester County compares with Massachusetts and the counties around it.
Each result puts Worcester County next to the 10 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Worcester County wells.
Arsenic10 of 64 wells over
Too few tested to show: Cheshire, NH, Franklin, Hampshire, Norfolk, Providence, RI, Tolland, CT.
This one is worth checking in Worcester County.
Manganese6 of 64 wells over
Too few tested to show: Cheshire, NH, Franklin, Hampshire, Norfolk, Providence, RI, Tolland, CT, Windham, CT.
These 3 are rare in Worcester County.
Uranium2 of 64 wells over
Too few tested to show: Cheshire, NH, Franklin, Hampshire, Norfolk, Providence, RI, Tolland, CT, Windham, CT.
Lead1 of 63 wells over
Too few tested to show: Cheshire, NH, Franklin, Hampshire, Norfolk, Providence, RI, Tolland, CT, Windham, CT.
Fluoride0 of 64 wells over
Too few tested to show: Cheshire, NH, Franklin, Hampshire, Norfolk, Providence, RI, Tolland, CT, Windham, CT.
Too few Worcester County wells were tested for these 2.
Nitrate4 wells tested
Radon in water2 wells tested
None of the 2 Worcester County wells tested for bacteria had it, but every well needs a yearly test.
Coliform bacteria0 of 2 wells had it
E. coli0 of 2 wells had it
E. coli means human or animal waste is getting in, so if a test of your Worcester County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 30 of 64 tested wells, and it isn't a health risk.
Iron stains30 of 64 wells had it
Too few tested to show: Cheshire, NH, Franklin, Hampshire, Norfolk, Providence, RI, Tolland, CT.
Worcester County has 64 tested wells, and the busiest decade for testing was the 2010s.
None of the 64 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Worcester 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 Worcester County.
- Bacteria
- Nitrate
- Arsenic
- Manganese
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 340 feet.
That comes from 24,873 household wells in Massachusetts's drilling records. Most wells of every kind here are 225 to 500 feet deep. Wells as deep as Worcester 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 go deeper than in 11 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 Worcester County.
Worcester County is in the EPA's highest radon zone. Radon from well water adds to the radon in your indoor air, so test your air first, and your water too if the air is high. Radon guide
Between 2023 and 2025 the EPA had 44 town water systems in Worcester County test for PFAS. 18 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 16 ng/L of PFOA. Only 1 well in Worcester County has 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 Worcester County
Is well water in Worcester County safe to drink?
10 of 64 wells tested in Worcester County had arsenic over the limit, about 2 in 10. Across Massachusetts it's about 1 in 15. That's the highest share among the 5 Massachusetts counties with 10 or more tested wells. So test your own well for arsenic before you count on it.
Where can I get my well tested in Worcester 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, arsenic and manganese, the tests that matter most in Worcester County.
How deep are wells in Worcester County?
Half the household wells here are shallower than 340 feet. Typical household wells here go deeper than in 11 of the 13 other Massachusetts counties with enough drilling records.
How does Worcester County compare with the counties around it?
For arsenic, the share of tested wells over the limit: 1 of the 4 neighboring counties with data had a higher share than Worcester County, at 16%. Hillsborough, NH had the most, at 17%. Groundwater doesn't stop at county lines, so Hillsborough, NH's 17% is worth knowing about if you live near it.
How often should I test my well in Worcester County?
None of the 2 wells tested for bacteria in Worcester 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 Worcester County numbers come from
- People on wells: 160,468 in Worcester County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 444 well water samples from 64 wells in the Water Quality Portal, run by the USGS and EPA, 2002 to 2019.
- Well depths: 24,873 Massachusetts drilling records for Worcester County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 10 counties that share a border with Worcester County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 44 town water systems in Worcester County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Worcester County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Massachusetts Department of Environmental Protection (MassDEP), checked November 1, 2026.