Can you flush eggshells with a septic tank?
The short answer for eggshells and a septic tank: trash. Eggshells are largely calcium carbonate that does not break down anaerobically; they sink and stay as grit at the bottom of the tank.
They add to the sludge layer, filling the tank and requiring more frequent pumping. Compost crushed eggshells or put them in the trash.
- Verdict
- Trash — they do not digest and add grit to the sludge layer
- Why
- Eggshells are largely calcium carbonate that does not break down anaerobically; they sink and stay as grit at the bottom of the tank.
- What it does to your system
- They add to the sludge layer, filling the tank and requiring more frequent pumping.
- Compost crushed eggshells or put them in the trash.
When in doubt, throw it out — only the three Ps (pee, poo, toilet paper) belong in a septic system.
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