What Not to Put in a Garbage Disposal (and Why)

01The never list, with the reason for each

A garbage disposal grinds soft food into particles small enough to flow down the drain with water. It is not a wood chipper and not a trash can. The items below cause the great majority of clogs, jams and burned-out motors, and each does its damage in a slightly different way. Understanding the "why" makes the list easy to remember.

• ·Grease, oil and fat: liquid when warm, they cool and solidify inside the disposal and drain line, coating everything and trapping other debris into a clog. They are the number-one cause of disposal and drain backups.
• ·Fibrous vegetables (celery, corn husks, artichokes, asparagus, onion skins): long stringy fibers wrap around the grinding plate and bind it, jamming the motor instead of being cut.
• ·Bones and fruit pits: too hard to grind, they bounce around the chamber, dull the components, and jam or damage the motor.
• ·Pasta and rice: they keep absorbing water and expand, swelling into a gummy mass that packs into the trap and drain line long after they go down.
• ·Potato peels: their starch turns into a thick paste that coats the chamber and clogs the drain, and small pieces slip under the grinding plate.
• ·Coffee grounds: they look harmless and grind fine, but accumulate into a dense, sand-like sludge that builds up and clogs the trap.
• ·Eggshells: contrary to the myth that they sharpen blades, the thin membrane wraps components and the shells grind into a gritty sediment that collects in the drain.

02Why grease and starch are the worst offenders

Two categories cause most of the serious clogs: fats and starches. Grease seems pourable when you tip the pan, but the disposal and the drain line beyond it are cool. The fat congeals into a waxy layer on the pipe walls, narrowing the line and grabbing every bit of debris that passes until the pipe chokes. No amount of grinding helps, because the disposal cannot change the temperature downstream.

Starchy and expanding foods, pasta, rice, potato peels, behave like a slow-setting glue. They keep swelling with water and compact into a paste that the grinding plate cannot break up and the drain cannot flush. This is why a sink can drain fine right after you run the disposal, then back up an hour later as the mass settles and expands in the trap.

When one of these does cause a backup, the disposal often is not broken at all, the drain past it is plugged. Our guide to a garbage disposal that is not working walks through telling a jam apart from a clog and clearing each safely before you call anyone.

03What you can safely grind

The list of what does not belong is longer than the list of what does, but a disposal still earns its keep. It is meant for the soft residue left after you scrape plates into the trash: small bits of soft cooked vegetables, fruit flesh, sauces, and the odds and ends rinsed off dishes. Run cold water before, during, and for 15 seconds after grinding so particles flush all the way through the line.

Cold water matters specifically because it keeps any small amount of fat solid so it grinds and flushes rather than coating the pipe. Treat the disposal as a finishing tool for residue and most of the failures on the never list simply do not happen, which is the surest way to reach the upper end of its lifespan. Our overview of how long garbage disposals last shows how much that care is worth in years.

04Habits that double a disposal's life

Beyond avoiding the never list, a few simple habits keep a disposal running smoothly. The goal is always to flush particles fully through the drain and keep the grinding chamber clean, so nothing accumulates to jam the plate or feed odors. Treated this way, a disposal reaches the far end of its service life rather than dying early and needing the labor of a replacement install.

• ·Always run a strong stream of cold water before, during, and after grinding.
• ·Feed scraps in gradually rather than packing the chamber full at once.
• ·Grind a few ice cubes occasionally to knock buildup off the components.
• ·Keep non-food items, twist ties, produce stickers, glass, metal, out entirely.
• ·Never reach into the chamber with the unit powered; jams clear safely only with the power off.