You CAN put eggshells down the garbage disposal, but your public water department may not approve.

The garbage disposal may be able to handle your eggshells ‘effortlessly', as stated by Insinkerator, a manufacturer of garbage disposals, but some water departments advise against it as eggshells are known to stick to pipes and clog sewage systems.

A Better Use of Eggshells

Rather than sending your eggshells down to the septic system, a better use for them is to add them to the compost pile. Eggshells can be easily composted and later used as a soil amendment in vegetable or flower gardens.

What NOT to Put Down the Garbage Disposal

Grease, oil, and fat coagulate once they hit cold pipes and have the potential to build up and clog your septic lines. Anything fibrous such as cornhusks or artichokes should not be put down the garbage disposal to prevent clogging. Some disposals have a tough time with hard items such as bones, popcorn kernels, and fruit pits. The CDC warns not to put contaminated food down the garbage disposal to prevent foodborne illness outbreaks.