A Faster Kitchen Fix: What You Need to Know About Garbage Disposal Installation Garbage disposal installation is a DIY-friendly project most homeowners can complete in 1 to 2 hours with basic tools — no plumber required. Here's the quick version of how it works: Shut off power at the circuit breaker Remove the old unit and disconnect the drain trap Install the new sink flange with plumber's putty Wire the unit and knock out the dishwasher plug (if needed) Mount the disposal,