While the drain connection for a garbage disposal is nearly universal and fits standard sink drain holes of 3 1/2 to 4 inches, the size of the disposal unit itself is not. You must have enough space in the cabinet underneath your sink to accommodate the disposal's housing. A larger model may not fit in a compact cabinet or if the existing plumbing is arranged in an unusual way. Before buying a new garbage disposal, measure the available space under your sink. If you are replacing an old unit, it's often easiest to choose a new model of a similar size.

On average, it takes one to four hours for a professional to install a garbage disposal. This includes removing the old unit, taking necessary measurements for positioning, removing and fitting new pipes, and installing the brand-new disposal system. If there are unforeseen issues, such as accessibility concerns, the process takes longer.

No, you do not need a garbage disposal to have a dishwasher. A dishwasher will work without one, and while it's rare to see a home with a dishwasher that doesn't have a disposal, it is possible. The two appliances pair well and are often installed together because a disposal simplifies meal cleanup.

However, your dishwasher should not be used as a replacement for a garbage disposal. Subjecting it to continuous food leftovers can lead to major clogs. If you choose not to install a garbage disposal, you should thoroughly rinse your plates or scrape excess food into the trash or a compost pile before loading them into the dishwasher to prevent plumbing issues.

You may be able to install a garbage disposal on your own, especially if you're handy or have some experience with plumbing. However, if you have any concerns or want to make absolutely sure that the connections are installed correctly, you may be better off hiring a local garbage disposal installer to do the job.