Soil is just one of the items you shouldn't put down a garbage disposal. Garbage disposals are only meant for soft, non-fibrous foods. Large amounts of topsoil, dirt, or rocks will damage the blades of your garbage disposal or clog the pipes. If a small amount of dirt goes down the drain as you repot a plant, you shouldn't have to worry, but never dump a whole pot of soil in the sink for fast disposal.

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.

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. 

The two main negatives of garbage disposals are they are a safety hazard in homes with children, and they frequently encounter blockage issues. While they might be annoying to fix and monitor, garbage disposals can significantly lower your trash use and are a great way to dispose of organic waste. While there are negatives, the vast majority of homeowners acknowledge the positives are enough to install a disposal in their home.