Drive north on High Range Road in Londonderry and nothing about the pavement changes. Same double yellow line, same mailboxes, same maple canopy pressing in over the road in August heat. But cross an invisible boundary near Royal Lane and the financial reality underneath two neighboring driveways splits in half. One house sits on a list to receive a paid connection to public water. The house across the street may not, and if it does, nobody outside the town has agreed to pay for it yet.
For a seller or buyer working with a private well anywhere near that corridor, this is not a footnote. It is the fact that should shape how you price, disclose, and negotiate a home in Londonderry right now.
What Changed On January 1, 2025
New Hampshire has required sellers to warn buyers about radon, arsenic, and lead paint for years under RSA 477:4-a. Starting January 1, 2025, the legislature added a fourth item to that same notification: PFAS. The exact language a seller now hands a buyer, before any purchase and sale contract gets signed, states that these chemicals have been detected at levels that exceed federal and/or state advisories or standards in wells throughout New Hampshire, but are more frequently detected at elevated levels in southern New Hampshire.
That statute sits alongside another one, RSA 477:4-d, which already required Londonderry sellers to disclose in writing the details of a private water supply and septic system, and which lawmakers amended in the same legislative window to add flood zone disclosure. Two separate updates landed on New Hampshire sellers in roughly the same year. For a home on a private well, both now apply.
The Line Is Not Hypothetical, It Is A Road
The contamination behind this law has a specific origin. In 2016, a tap water sample collected inside Saint-Gobain's Merrimack manufacturing facility tested positive for PFOA. The investigation that followed found the chemical had traveled through the air and settled into groundwater across a wider footprint, eventually turning up in wells in Bedford, Hudson, Litchfield, Londonderry, and Merrimack. Under a 2018 consent decree, Saint-Gobain agreed to provide clean drinking water solutions to roughly 1,000 affected properties across those five towns.
Londonderry sits at the edge of the roughly 65-square-mile zone the company is legally bound to remediate, and that zone happens to split the town along High Range Road. On March 31, 2026, the town, the state, and Saint-Gobain finalized an agreement covering Phase II of the High Range Road water main. Saint-Gobain will fund 40 percent of the project, or $1,717,378.40 of the estimated $4,293,446 cost, and will hold another $410,344.60 in escrow to cover overruns. Phase I was completed in 2025. Phase II is scheduled to wrap by fall 2026, extending the line north from Royal Lane toward the rest of the affected stretch.
That construction will connect an estimated 350 properties on the west side of High Range Road to a public system operated by Pennichuck Water Works. On the east side of the same road, contamination has shown up in even more homes, and Saint-Gobain has no legal obligation to pay for any of it. Londonderry Town Manager Shaun Mulholland has estimated that between 600 and 800 residents there will eventually need a public water connection the company isn't funding.
"The residents of Londonderry did not cause this problem. They did not ask for this problem." — Ron Dunn, Londonderry Town Council Chair
| West side of High Range Road | East side of High Range Road | |
|---|---|---|
| Funding source | Saint-Gobain (40%) plus NH Drinking Water and Groundwater Trust Fund | No Saint-Gobain obligation; town and state funding only |
| Homes affected | Roughly 350 properties | An estimated 600 to 800 residents, with more wells testing positive over time |
| Connection timeline | Phase II construction targeted for completion by fall 2026 | Part of 12 priority projects town-wide, roughly $45 million, multi-year |
| What it means at closing | Ask the seller to confirm hookup status and whether any assessment remains | Ask whether the property falls inside a proposed special assessment district |
What The $275 Million Number Actually Means For Your Closing
Mulholland has put the town's full price tag for addressing PFAS contamination at more than $275 million once every affected household is accounted for, a figure he says will exceed all of Londonderry's other capital expenses combined. That number will never appear on a listing sheet. Years from now it shows up as either a hookup date already on the calendar or a new line on a property tax bill.
Town officials floated a way to handle the second scenario in January 2026: special assessment districts, which would let homeowners outside the Saint-Gobain-funded zone add the cost of connecting to public water onto their property taxes over as long as 20 years, rather than paying the full hookup cost at once. Warrant articles addressing this plan were headed to Londonderry's March 2026 town meeting. We did not find confirmation of the specific vote outcome in available reporting, which means anyone pricing or evaluating an affected property should call the town's administrative services office directly rather than assume the status quo.
There is also relief available that a lot of sellers do not realize exists. Residents outside the Saint-Gobain boundary whose well tests above New Hampshire or EPA limits can apply to the state's PFAS Removal Rebate Program for up to $5,000 toward a treatment system, or up to $10,000 to connect to public water instead. That changes the negotiation. A failed PFAS test does not automatically mean the seller eats the full cost of a fix.
Before You List Or Make An Offer On A Well-Served Londonderry Home
- Test the well specifically for PFAS. A standard private well panel typically checks bacteria and nitrates. PFAS is usually a separate, add-on test, and an old water test that predates this concern will not answer a buyer's question.
- Confirm which side of High Range Road the property sits on, and whether it falls inside the roughly 350-property zone with a funded, dated connection or the larger area still being sorted out.
- If the property is outside the funded zone, ask the town directly whether the special assessment district plan has moved forward and what a future hookup could add to the tax bill.
- Check eligibility for the PFAS Removal Rebate Program before either side assumes remediation cost falls entirely on the seller.
- Build the PFAS notification into your timeline early. Under RSA 477:4-a, it has to reach the buyer before a purchase and sale contract is signed, not folded into paperwork at closing.
Outside The Boundary Does Not Mean Outside The Conversation
None of this is confined to High Range Road. Statewide, New Hampshire's Department of Environmental Services had identified more than 3,000 wells testing above state PFAS limits as of 2024 reporting, roughly 27 percent of all wells tested to that point, with detections running higher across southern New Hampshire generally. A buyer looking at a Colonial off Mammoth Road or a split-level well outside the Saint-Gobain boundary is still buying into a town where the disclosure language exists for a reason. A fresh well test costs far less than an assumption that turns out wrong after closing.
A Short FAQ
Does every Londonderry seller have to test their well for PFAS before listing? No. RSA 477:4-a requires notification, not mandatory testing. But the notification exists so a buyer can request testing, and a seller without recent results is negotiating from a weaker position the moment a buyer asks for one.
If my home is already on town water, does any of this apply to me? The PFAS notification under RSA 477:4-a applies regardless of water source. The special assessment district and funded connection zone discussion applies only to private well owners inside or near the affected area.
Will connecting to the new water main show up as a tax increase right away? Not necessarily right away. The special assessment approach under discussion would spread hookup costs over as long as 20 years instead of billing the full amount upfront, which is exactly why it belongs in a buyer's due diligence conversation rather than a surprise discovered after closing.
Londonderry's water story is still being written street by street, and what a well-served home here is actually worth depends on which side of that story your address falls on. If you are weighing a sale near High Range Road, or evaluating any well-served property in town, Granite State Realty Group can walk the specific parcel, the specific zone map, and the specific numbers with you before you list or write an offer. Request a free local market consultation and get answers built around your address, not the town average.
