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.

On average, a garbage disposal can last anywhere from 7 to 12 years, with many models functioning well for about 10 years. With heavy usage, a motor may last a minimum of five years, while grinding plates will wear down over time. It's generally a good idea to consider a replacement if your unit is approaching the 10-year mark. Other signs that it's time for a new disposal include frequent leaks, persistent clogs, lingering odors, lack of power, or unusual noises. If your unit is not that old, it's worth investigating if a less expensive part, like a rubber seal or a loose hose, is causing the issue.

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. 

If your garbage disposal powers up and you can hear it hum, but the arms inside aren’t moving, the problem might be a stubborn clog, a build-up of grease, or a jam of the impeller plate. To troubleshoot these, ensure your unit is off and disconnected from its power source before checking inside the drain or attempting to manually rotate the impeller arms or plate from the underside of the unit. A hex wrench can help.