Finding Plumbing Issues Early

Replacing Your Kitchen Garbage Disposal Unit

by Chris Bowman

Your garbage disposer has become noisy and it may take two or three tries to get food to go down it. It's time to replace that unit and, if you buy the same model, you can do the replacement yourself. If you buy a different brand or model, or you're uncomfortable working with plumbing and electricity, have a plumbing service come out and do the work. If you're a DIY kind of homeowner, here are the steps to replace that old disposal unit.

What You Need for This Project

  • flat-blade screwdriver
  • small pipe wrench or channel lock pliers
  • plumber's putty (may be optional)
  • small bucket
  • couple of rags for cleanup

Safety note: Be especially careful doing kitchen repairs that involve both water and electricity. The combination puts you at risk of being shocked.

Removing the Old Disposal Unit

  1. Find the switch in the circuit breaker box that controls the garbage disposal and turn it off.
  2. Clear out the items from under the kitchen sink so you have room to work.
  3. Turn off the water valve under the sink.
  4. If the unit is plugged into an electrical outlet under the sink, unplug it now. Otherwise, it will be connected to wires that go through a conduit into the wall, and you'll deal with them later.
  5. Find the drain pipe attached to the side of the disposer and remove it. This pipe is typically held on by a large nut that you'll unscrew or a spring clamp that you loosen with the pliers.
  6. Push up slightly on the disposal unit while turning it counterclockwise to remove it from the mounting flange. The unit is heavy, so don't let it fall out of your hands.
  7. Turn the unit over the bucket to drain out any water and debris.
  8. Place the unit upside down on the floor so you can access the electrical wires.
  9. Remove the plate that covers the wires going into the unit. Remove the ground screw and the wire nuts connecting the house wiring to the unit. You're done with the old disposer now.
  10. Remove the screws holding the mounting ring to the flange. Remove the mounting ring.
  11. Unscrew the metal ring holding the flange to the sink. Push the flange up out of the sink.
  12. Clean any old sealer from around the drain in the sink.

Preparing the Sink for the New Disposal Unit

  1. Position the rubber seal around the bottom of the flange that came with the new disposer.
  2. Lower the flange through the sink drain hole.
  3. Place the other rubber seal on the flange under the sink then screw the metal ring onto the flange until it makes a secure seal with the sink drain hole.
  4. Attach the mounting ring to the flange with the screws provided with the new unit. Tighten the screws evenly so the ring is level with the bottom of the sink.

Installing the New Disposal Unit

  1. Turn the new unit over onto the floor and remove the metal plate covering the electrical connections.
  2. Connect the wires coming out of the wall, or from the plug, to the wires under the cover. Screw the green or copper ground wire to the green terminal on the unit. Connect the two white wires together and secure with a wire nut. Do the same with the two black wires. Replace the cover plate.
  3. Turn the garbage disposal over and lift it onto the flange. The mounting ring on the unit will screw onto the mounting ring on the flange. Turn the unit so you can access the drain port.
  4. Attach the drain pipe to the unit with the large nut or spring clip.
  5. Plug the unit into the wall if necessary.
  6. Turn the water on under the sink.
  7. Run water in the sink for a few minutes and look for leaks.
  8. If no leaks are present, then turn the power back on to the disposer.

Problems You May Encounter

  • If you purchased a different unit than the one you are replacing, the mounting hardware to the sink will likely be different. You may want a professional plumber, like those at Aumenta Plumbing & Heating Co., to install this unit and the new hardware.
  • If the unit did not come with two rubber seals for the flange, use plumber's putty to create a watertight seal between the metal parts and the sink.