Debunking The Myth: Why It's Not Actually Safe To Put Eggshells In Your Disposal

There are many misconceptions and myths when it comes to that most finicky, convenient, and intimidating of kitchen appliances: the garbage disposal. "Run it with hot water" — actually, cold water is better for ensuring grease and fats don't melt and reform further in the pipes, causing clogs. "Use ice cubes to sharpen the blades" — while the idea of ice cubes sharpening the blades is a myth, they are actually good for cleaning the mechanism, similar to how ice cubes and kosher salt can clean stubborn coffee residue from travel mugs. One of the most prevailing myths about garbage disposals is that it's okay, or even beneficial, to put eggshells down them.

The enduring idea is that putting eggshells down the drain will keep the blades sharp and the machine running smoothly, but that's wrong for several reasons. The first reason is that, contrary to popular wisdom, garbage disposals don't actually have blades — at least, not in the conventional sense. Often, people imagine the blades of a blender or coffee grinder, but it's more accurate to imagine a cheese grater grinding the food into minuscule pieces that can safely go down the pipes.

The other reason is that eggshells not only fail to sharpen the blades, but also contain a thin membrane that anyone who has failed to crack an egg on the first try is undoubtedly familiar with. That membrane can get wrapped around a garbage disposal, causing it to clog and restrict movement.

Eggshells aren't the only food item that doesn't belong in the garbage disposal. Some are obvious: bones, oyster shells, and corn husks will all damage the spinning blades and can cause major issues for your disposal. 

Other items might not be as obvious. Coffee grounds should never go down the garbage disposal, as they can obstruct movement and build up over time, causing clogs. Think of them as a grain of sand in the gears. Onion skins are problematic for the same reason as eggshells — remember that slinky membrane that sits just below the dry skin of the onion? That can cause serious issues. Bread and pasta are also surprisingly harmful, given their propensity to expand in liquid. It may seem like they should be chopped up without much effort, which is true in small quantities, but put enough down there and these grains will grow and compact, causing serious blockages.

The good news to the reducers, reusers, and recyclers out there is that there are plenty of ways to use eggshells around the house that have nothing to do with the garbage disposal. Fertilize your plants, use sterilized, crushed eggshells to provide calcium supplements for your pets, or even make a DIY whitening toothpaste — just make sure to have a storebought one on hand, as this is more for cosmetic purposes than cavity-prevention.