Your garbage disposal will only affect the health of your septic tank if you’re using it too frequently, or filling it with organic waste that doesn’t fully break down. If the tank fills up with too many solids, the bacteria won’t have enough time to consume it before more is added, which can lead to an overflow in the drain field. Your tank will need to be pumped more frequently with excessive or improper garbage disposal use.

These appliances certainly increase the number of things allowed down the drain, but they’re not foolproof. There are several items you shouldn’t put in your garbage disposal, according to manufacturers and technicians. Don’t put coffee grounds down the drain. The same goes for eggshells, potato peels, hard foods, onion skins, and any dry, expandable food. Most importantly, never put grease or oils down the drain.

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. 

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.