How to Install a Garbage Disposal

Garbage disposals are almost ubiquitous in today’s modern kitchens. Even if you meticulously scrape your plates, pots, and pans, some amount of food waste is bound to go down the drain. A garbage disposal will grind up that food waste and keep you pipes running cleanly. If you have been thinking about installing a garbage disposal or wish to upgrade and want to learn how to replace a garbage disposal, this blog post will guide you through the DIY garbage disposal installation process.

With any plumbing project, when performing a garbage disposal installation or replacing a garbage disposal, it is better to start the project early in the day. That way of you need to visit the plumbing or hardware store, for forgotten or extra tools, fixtures or materials, you have time. Never begin a project when the hardware store will be closed for several hours. Be sure to gather all materials and thoroughly read the directions. Double check that you have all parts and materials called for in the installation instructions and thoroughly understand how to remove a garbage disposal and install a new one before you begin.

Items Needed:

  • Circuit tester
  • Flat head screwdriver
  • PVC saw
  • Adjustable plier
  • Plumber’s putty
  • Electrical caps
  • Wire nuts
  • Electrical tape
  • Bucket
  • Gloves
  • Towel

How to Install a Garbage Disposal for the First Time (No Old Garbage Disposal)

Each garbage disposal is a little bit different. Your garbage disposal will come with installation directions. Be sure to follow the directions carefully. Most images used here are from InSinkErator, a dependable and quiet garbage disposal manufacturer.

  • First, you’ll need to make sure your garbage disposal fits under the sink and that your garbage disposal has power. If you do not have an outlet under the sink, you’ll need an electrician to install a power outlet.

  • Turn off the power at the breaker box. Cover the box or place a warning sign at the box so that no one will accidentally turn the power back on while you are working.

  • Use channel lock pliers to remove the down drain pipe and P trap. Then unscrew the nut holding the sink strainer in place and remove the strainer and clean off the old plumber’s putty

  • Place a new ring of plumber’s putty around the drain opening and place the new sink flange into the drain opening and press it firmly in place. Place some type of weight on to flange to help it in place. (May use the garbage disposal itself.)

  • Slide the fiber gasket and backup ring up the flange under the sink and then slide the mounting ring and snap ring up the flange.

  • Slid the mounting screws into place. Alternate tightening each screw a few times until the mounting assembly is even and tightly seated to the sink.

  • The disposal has a dishwasher knock out plug. If you do not have a dishwasher, ignore this step. Lay disposal on its side and use a screwdriver and hammer to knock out the plug. Remove the loosened knock out plug from inside the disposal.

  • Next, you’ll connect the electrical connections. Lay the disposal on its side and remove the plate on the bottom of the disposal and use wire connecters to connect the wires on the disposal to the power supply. Secure the power cord to the bottom of the disposer. Replace the power plate.

  • Now it is time to mount the garbage disposal unit. Align the tabs on the disposal with the slide up ramps on the mounting ring. Hold the disposal in place and turn the mounting ring until all tabs are locked into place.

  • Insert the discharge tube into the discharge coupler. Slide the clamp up the discharge tube and place it in the groove. Rotate the disposer until the discharge tube is aligned with the drain trap. You may have to cut off some of the tube if it is too long. Use a drain hose to attach the dishwasher inlet, if you have a dishwasher.

  • Lock the garbage disposal to the sink mounting assembly using the wrench that came with the garbage disposal. Insert the sink baffle opening by pressing it into the sink drain.

  • Test for leaks at the sink flange, dishwasher, mounting assembly and tail pipe connections. Turn the electricity back on and test the garbage disposal’s operation. Congratulations, you now know how to install a garbage disposal!

How to Change a Garbage Disposal

  • Turn of the electrical power at the circuit breaker box. Cover the box and post a sign so that no one may turn the power back on unexpectedly. Remove the cover on the base of the old garbage disposal. Next, loosen the ground screw and detach the wire connectors.

  • Disconnect the dishwasher connection and the drain crosspiece by loosening the bolts that connect the disposal to the drain flange.

  • Most garbage disposal attach with a three tab mounting ring. Holding the garbage disposal from below, rotate the ring counterclockwise until the garbage disposal detaches. Detach the retaining ring, drain, and clean away the old plumber’s putty.

  • Now that the old garbage disposal has been removed, you can attach the new one. Follow the steps listed above in How to Install a Garbage Disposal.

Installing or changing a garbage disposal entails many different steps, but it is not too difficult when you break it down step by step. A leaky or malfunctioning garbage disposal can cause thousands of dollars worth of damage to floors, structure, and cabinetry. Take your time and review each step of the process before beginning the installation. It you need help or run into unexpected problems with your garbage disposal installation, call a plumber.