Garbage disposals are durable appliances that usually last at least eight years as long as you clean and maintain them. It’s relatively rare for a garbage disposal to break on its own, as most malfunctions happen due to user errors, like overstuffing the grinding compartment or damaging the blades by trying to dispose of metal or bone. Eventually, cracks or leaks could develop in the unit, which requires a full replacement. 

Replacing a garbage disposal costs anywhere from $150 to $950, but the average cost is somewhere around $550. There are two types of garbage disposal units, and continuous feed disposals tend to cost more than batch feed disposals. Going for an aluminum garbage disposal is also significantly cheaper than choosing a stainless steel garbage disposal. You'll also need to factor in the horsepower of the motor, labor, and the removal and disposal of your old unit.

There are many maintenance and repair issues that lead to a malfunctioning garbage disposal. Regular clogs place wear and tear on the motors, leading to an eventual shutdown. Electrical issues at the breaker, wall outlet, or disposal itself can fry the unit. The most common cause is simply a worn-down motor. These motors can only handle so much use before powering down for good. 

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.