Why Flushing Your Septic System Now Protects Southern NH’s Waters

On a brisk April morning along the shores, the ice has finally receded, revealing a landscape eager for spring. But beneath the surface, another thaw is underway, one that could spell trouble for the region’s cherished waters if homeowners neglect a crucial spring ritual: flushing and pumping septic systems.

April marks a turning point for septic systems across southern New Hampshire. As the ground thaws, accumulated solids and fats in septic tanks are mobilized, just as melting snow and spring rains saturate the soil. This combination overwhelms the soil’s ability to absorb and treat wastewater, especially in areas with high water tables. The risk? Untreated effluent can back up into homes, surface in yards, or seep into nearby water bodies, a scenario that’s all too common after a long winter when biological activity in septic tanks slows to a crawl.

The timing couldn’t be worse. Spring brings a surge in household water use, from returning seasonal residents to deep-cleaning routines. Yet, after months of cold-induced dormancy, septic systems are at their least efficient. The NHDES recommends pumping septic tanks every 3 to 5 years, but in New Hampshire’s high-risk spring conditions, more frequent maintenance is often necessary to prevent costly and sometimes irreversible damage, such as drain-field failure or sewage backups.

The consequences of neglect extend far beyond individual properties. Failing septic systems are a source of nitrogen and phosphorus pollution in southern New Hampshire’s lakes, ponds, and rivers. These nutrients fuel harmful cyanobacteria (blue-green algae) blooms, which have plagued our lakes across NH. In some areas, septic systems contribute to the 903 tons of nitrogen entering the water each year, degrading water quality and threatening aquatic life.

What goes down the drain matters, whether on a septic or sewer system.  Please do not flush unused prescriptions; those drugs enter local waterways, disrupting aquatic life and threatening ecosystems. PFAS chemicals from household cleaners compound the problem, turning up in water bodies. I urge residents to use drug take-back programs rather than drains, a simple step that keeps both pharmaceuticals and communities healthier

For homeowners, the message is clear: schedule your septic system inspection and pumping this April. It’s a simple step that protects our water bodies.