Be septic smart to protect New Hampshire waters

If you own a home with a septic system, one of the most important things you can do to protect our lakes is keep it maintained. When working properly, it quietly treats wastewater before it filters into the ground. But when aging, neglected, or poorly maintained, these systems can become a serious source of pollution.

That risk is especially significant in New Hampshire, where roughly 85% of households rely on septic systems rather than sewers. You don’t have to live right on the shoreline to make a difference, but waterfront properties pose a higher risk since wastewater there has less distance to travel before reaching the lake.

The problem lies in nutrients like phosphorus and nitrogen, which are found in wastewater. A failing or outdated system can leak those nutrients into the groundwater that flows into the lake. Once there, they act like fertilizer, feeding algae and cyanobacteria that decrease water clarity, harm fish and wildlife, and can even create health risks for people.

Even systems that appear to be “working” on the surface can slowly leak wastewater underground if they’re more than a few decades old. Over time, pipes may crack from shifting soils or root intrusion, and leach fields can lose their ability to filter properly.

Homeowners may not notice any backups, odors, or wet spots in the yard, yet the system could still be quietly releasing a steady stream of nutrients into the groundwater, and eventually into the lake. Given that many lakefront homes sit on sandy soils where water moves quickly, the lake can feel the effects before you even realize something is wrong.

The good news is that taking care of your septic isn’t complicated, and simple steps can keep it working as intended for years. Regular pumping and inspections are essential, ideally every two-to-three years for pumping, and every five-to-seven years for a full inspection depending on the system’s age and use.

Pumping clears out the solids that naturally build up over time, while inspections can alert you to small issues before they turn into big, expensive problems. A cracked baffle or a clogged line might not seem urgent today, but catching it early can extend the life of your system by years and save you thousands of dollars down the road. Just as importantly, staying ahead of problems protects your investment in your property while also protecting the lake.

In July 2024, New Hampshire passed HB 1113, a law that changes how septic systems are handled during waterfront property sales. The legislation requires a septic inspection if the system is within 250 feet of a lake, river, or other protected waterbody and is more than 20 years old, or if its age cannot be determined.

If the inspection shows the system is failing, it must be repaired or replaced within 180 days after the sale is completed. The buyer and seller may come to an agreement on who will cover the cost, and that agreement must be documented as part of the transaction. To ensure follow-through, licensed evaluators are required to file failure reports with NHDES and the local health officer, creating an official record and a clear, enforceable timeline for compliance.

For those of us who love the lake, it’s worth remembering that septic care is lake care. Keeping your system healthy protects your investment, but it also protects the waters we recreate in. As nutrient pollution continues to be one of the leading threats to clean lakes across New Hampshire, every homeowner’s actions matter.

For more tips on how to keep your system working properly, visit the EPA’s SepticSmart program at epa.gov/septic/septicsmart.

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Bree Rossiter is the conservation program manager for the Lake Winnipesaukee Alliance. She manages the water quality monitoring program, cyanobacteria monitoring initiatives, the Winni Blue/LakeSmart program, and assists with watershed management planning efforts. Bree can be reached at brossiter@winnipesaukee.org. The Lake Winnipesaukee Alliance is a nonprofit dedicated to protecting the water quality and natural resources of the lake and its watershed. To learn more, visit winnipesaukee.org.