PFHxS in well water
1in8
private wells tested in Kent County, Michigan had pfhxs above the limit, the highest share of any county, according to EGLE North Kent Study Area residential well PFAS results.
PFHxS comes mainly from firefighting foam and persists in the body longer than most PFAS. It is linked to thyroid and immune effects. Wells near airports, fire stations and training grounds are most at risk.
- EPA limit
- 10 ng/L (EPA MCL (2024 PFAS rule; proposed for rescission May 2026); New Hampshire MCL is 18 ng/L)
- Michigan level
- 10 ng/L
- CAS number
- 355-46-4
Check your PFHxS number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Test your own well for 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.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove PFHxS
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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 PFHxS
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For PFHxS
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 PFHxS
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.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where pfhxs is worst, by homeowner tests
Counties ranked by the share of private wells above the state guidance level in tests homeowners sent to the state lab. Shares combine town summaries, weighted by wells tested.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Kent County, Michigan | 1,595 | 21,000 ng/L | |
| Nantucket County, Massachusetts | 48 | 37.1 ng/L | |
| Dukes County, Massachusetts | 77 | 42.1 ng/L | |
| Middlesex County, Massachusetts | 274 | 704 ng/L | |
| Bristol County, Massachusetts | 144 | 14.1 ng/L | |
| Barnstable County, Massachusetts | 83 | 94.2 ng/L | |
| Worcester County, Massachusetts | 185 | 14 ng/L | |
| Franklin County, Massachusetts | 323 | 6.9 ng/L | |
| Hampshire County, Massachusetts | 174 | 9.4 ng/L | |
| Berkshire County, Massachusetts | 174 | 7.5 ng/L | |
| Hampden County, Massachusetts | 116 | 8.1 ng/L | |
| Plymouth County, Massachusetts | 110 | 6.63 ng/L | |
| Essex County, Massachusetts | 67 | 6.49 ng/L |
By individual samples
Counties with at least 30 individual samples in public monitoring data, against the EPA limit.
| County | Above EPA limit | Samples | Detected | Median |
|---|---|---|---|---|
| Washington County, Maine | 36 | 25% | 0 ng/L | |
| Franklin County, Maine | 44 | 16% | 0 ng/L | |
| Somerset County, Maine | 575 | 36% | 0 ng/L | |
| Oxford County, Maine | 72 | 18% | 0 ng/L | |
| Penobscot County, Maine | 294 | 26% | 0 ng/L | |
| Sagadahoc County, Maine | 170 | 22% | 0 ng/L | |
| York County, Maine | 385 | 36% | 0 ng/L | |
| Lincoln County, Maine | 110 | 35% | 0 ng/L | |
| Aroostook County, Maine | 113 | 23% | 0 ng/L | |
| Hillsborough County, New Hampshire | 3,793 | 82% | 0.79 ng/L | |
| Waldo County, Maine | 401 | 18% | 0 ng/L | |
| Cumberland County, Maine | 573 | 43% | 0 ng/L | |
| Kennebec County, Maine | 450 | 27% | 0 ng/L | |
| Strafford County, New Hampshire | 157 | 57% | 0.21 ng/L | |
| Rockingham County, New Hampshire | 2,122 | 81% | 0.87 ng/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure pfhxs at the levels that matter. Collect from the kitchen tap before any treatment, and again after treatment if you install it.
How to treat
- Granular activated carbon whole-house
- Point-of-use reverse osmosis
- Anion exchange
Analysis: PFAS in private wells: known sources versus routine testing, from the same public records.