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Fact Sheet

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A septic system is a sewage treatment and disposal system buried in the ground. It is composed of a septic tank and a leach field or trench. Septic systems can fail due to poor design or construction, to overloading or to inadequate maintenance.

Improperly functioning and overloaded septic systems are major sources of water pollution. Failing septic systems leak harmful pollutants, like bacteria and excess nutrients (nitrogen and phosphorus), into groundwater. From there, pollutants make their way into lakes, streams, rivers, and coastal waterbodies.

Many homeowners are under the misconception that a septic system, once installed, will work forever without maintenance. This is not true! Most septic systems, even with maintenance, will work effectively for only an average of 15 to 25 years. To help protect against premature failure, the homeowner can follow a few simple procedures. These procedures help reduce sludge build-up, reduce water use, eliminate toxic waste, keep the system’s bacteria working and protect the leaching system. To see if you are treating your septic system properly, review the checklists on the following pages.


Adapted from Maine DEP publication #DEPLW-57 Written by Frank O'Hara, Illustrations by Jon Luoma


Toxics; Nutrients; Casco Bay Estuary Partnership, Fact Sheets





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