As a child, I was always fascinated with garbage disposals. We didn't have one in our home, so I loved to watch them chew up and swallow dinner scraps when I visited friends with these marvels of mechanical wonder. Carrots or celery stalks were a personal favorite to watch as they danced their downward spiral. I wondered, where did all that stuff go? How did this machine work?
If you've never had the nerve to peek inside the disposal with a flashlight, you might wonder too. In essence, the disposal is like a circular food grater with spinning metal hammers to quickly rub the food scraps around the inside of the circular grater. Food particles that are ground fine enough wash through the grater screen and down the drain. Larger chunks stay until they are sufficiently broken and ground. Really hard chunks like bones (or an occasional fork) clatter around making lots of noise. Retrieving those items (ALWAYS unplug the disposal first) will give you a graphic reminder of why fingers NEVER go in a disposal.
Garbage disposals offer convenient processing and disposal of soft food scraps. However, they should be used sparingly in homes with private septic systems. Why? Consider where those food particles go. All this additional organic matter ends up in your septic tank. Given sufficient time and space, the septic tank can decompose those food scraps. But most septic systems are not designed and sized to handle this extra organic load. Particularly in homes already serving large families, this extra load can tax the microorganisms already working to decompose organic matter in your sewage.
Overloaded septic tanks can pass undigested organic matter into the soil absorption field where it plugs the soil pores causing the whole system to fail. Even if the septic tank isn't overloaded to the point of failure, the extra organic load will cause faster sludge accumulation in the bottom of the septic tank. You'll be faced with more frequent septic tank maintenance.
Occasional light use of garbage disposals is fine. But for most of your decomposable table waste and especially for large quantities like food canning or processing waste, consider another great alternative: composting. Compost piles are ideal for decomposing organic wastes like fruit and vegetable scraps, turning them into a valuable product for your garden or yard. Organisms still decompose the food waste, but rather than sludge in your septic tank, the byproduct is the rich humus-like material gardeners crave.