Non-food items can easily damage or break a garbage disposal, leading to costly repairs. Never put metal, glass, paper or plastic objects in the garbage disposal. A major culprit of disposal damage is silverware, which can easily fall into the disposal without the homeowner noticing. To prevent this problem, clear the sink of all dishes and silverware before running the disposal. Keep a strainer basket over the disposal when it's not in use so nothing falls into the unit.
Do not run hot water down the drain when running the garbage disposal. Hot water can cause grease to liquefy, which can accumulate around the blade and clog the drain. It may also cause some food products like pasta to expand or create a paste with flour. It is OK to run hot water down the drain if the garbage disposal is clear.
Fibrous or stringy foods can wrap around a disposal blade, burn up the motor and clog the drain. Some fibrous foods are acceptable, but avoid grinding extremely fibrous foods like celery stalks, corn husks, stringy squash and onion skins. These foods are OK in small pieces in which the strings are not long enough to wrap around the blade.
Foods like pasta and rice can expand in the garbage disposal and clog the drain. This is a bigger danger if the food is added when hot or if hot water is run during disposal. If you dispose of a large amount of these foods, you could potentially pack the drain for several feet, leading to expensive plumbing repairs.
Large animal bones are not meant to be ground in the garbage disposal. The blades and motors are too small to handle large bones like steak bones or poultry carcasses. Some small bones are acceptable and may actually help keep the blades sharp and the walls of the disposal clean.
Avoid adding too many potato peels, especially at one time. The starches in potato peels create a paste around the blade that can keep it from turning. Cleaning the blade of the sticky paste is especially difficult.
Grease and Fats
Avoid putting grease, oil or other fats down your garbage disposal drain. Some people claim that it is safe to put solidified grease in the garbage disposal because the blades will chop it into small pieces that can fit down the drain. The main danger with grease is that it could liquefy and then solidify further down the pipe. Even small pieces of solidified grease can accumulate in the sewer and cause major damage.
Dispose of hazardous materials through your community's hazardous materials disposal system, not the home garbage disposal. Putting them down the drain means they eventually end up back at the sewage treatment plant. If you have well water, these materials could potentially end up in your ground water or local streams. Hazardous materials include household cleaners, pesticides, paint, motor oil, medicine and other chemicals.