Q: I want to buy a waterfront property with a septic system. What should I be aware of before doing so?
New Hampshire has strict septic system inspection requirements prior to the sale of waterfront properties. Under RSA 485-A:39, any developed waterfront property that uses a septic system, and where any part of that system is within 250 feet of the shoreline, triggers mandatory evaluation requirements if the property is sold. Importantly, the law places the primary responsibility on the buyer, not the seller. Before such a property is transferred, the buyer must hire a New Hampshire licensed septic system evaluator to inspect the system, at the buyer’s expense. There is one limited exception: a buyer may rely on a seller’s existing evaluation, but only if it was completed within the prior 180 days and is formally accepted in writing.
In some cases, the review goes a step further. If the septic system was never formally approved by the State, or was approved before September 1, 1989, the buyer must also hire a permitted septic system designer. That designer evaluates whether the system meets modern standards, specifically, whether it sits high enough above the seasonal high-water table. This determines whether the system is considered to be “in failure.”
Importantly, a failed inspection does not stop the sale. The law is designed to ensure disclosure and accountability—not to block transactions. However, it does carry real consequences. If the system shows signs of failure, the buyer must provide notice to State and local officials and is generally required to repair or replace the system within 180 days after the purchase. Proof of that replacement must then be filed with the State. Alternatively, a buyer can choose to skip the evaluation entirely, but only by committing upfront to replace or repair the system within that same 180-day window and notifying regulators of the buyer’s intent before closing.
These requirements are rooted in environmental concerns. Septic systems located near lakes and rivers, if not functioning properly, can release nutrients like nitrogen and phosphorus, as well as bacteria, into nearby waters. Over time, this could contribute to algae blooms, reduced water clarity, and degraded habitat—issues that have affected many of New Hampshire’s waterbodies.
For buyers, the takeaway is clear: purchasing a waterfront home in New Hampshire now comes with affirmative legal obligations tied to the septic system. These requirements can affect cost, timing, and even whether a property is a feasible investment. For sellers, while the burden in on the buyers, providing a recent inspection can still help facilitate a smoother sale. For anyone considering a waterfront purchase, understanding these rules is not just good practice, it is part of the deal.
Know the Law is a bi-weekly column sponsored by McLane Middleton. Questions and ideas for future columns should be emailed to knowthelaw@mclane.com. Know the Law provides general legal information, not legal advice. We recommend that you consult a lawyer for guidance specific to your particular situation.