How to Replace a Garbage Disposal

14 ways to avoid leaks and mistakes

When you flip the switch to turn on the garbage disposal and all you get is a hum—or a loud, metal-on-metal grinding noise—you know something’s wrong. Fortunately, replacing a disposal isn’t hard, even if you haven’t done much plumbing. We talked to veteran plumbers and collected their best tips for a smooth, trouble-free installation.

By the DIY experts of The Family Handyman Magazine

TIME

One day

COMPLEXITY

Simple

COST

$100 - $500

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Make sure it's really broken

  • Look for a jam. Something too tough to grind, such as a piece of glass, could be jamming the motor. Turn off the power and water, then unplug the disposal. (If it’s hardwired, turn off the breaker.) Remove the rubber baffle inside the drain—most just lift out—and shine a flashlight into the hole. Fish out the obstruction with a pair of tongs or needle-nose pliers.
  • Turn the motor manually. You’ll need a hex wrench. Some disposals come with one bent at a convenient angle, but if you don’t have it, you can buy one at a hardware store or use a standard Allen wrench. Rotate the wrench back and forth as shown above until the motor turns a full revolution, then remove the wrench and switch on the motor.
  • Press the reset button. If your motor has overheated by working too long, wait five minutes for it to cool down, then push the reset button. (It’s usually located on the underside of the disposal.) The motor may also have overheated because of a jam. If the motor doesn’t start after manually turning it, try pushing the reset button.

Knock out the knockout!

Everyone who’s installed a few disposals is aware of this mistake: Forgetting to remove the dishwasher knockout before hanging the unit.

If you have a dishwasher, the first thing you should do after removing the disposal from the box is to punch out the knockout with a hammer and a screwdriver. Fish out the knockout by reaching down inside the disposal. You don’t want this plastic disc to be the first thing that the disposal tries to grind up!

This is also the best time to add the cord and plug to your disposal. It’s really awkward to add these after the disposal is installed.

Figure A: Figure it out first

When you buy a new disposal, the box will contain all the parts you need to install it. Before you jump into removing the old unit, take a few moments to familiarize yourself with all these parts. Put them together in the correct order and try out the locking mechanism. Understanding how everything fits together ahead of time will make the job a cinch.

Figure A

Disposal system anatomy

Support the weight

Don't forget the cord

Prepare for a new discharge tube

Shortcut: Keep the flange

If your old sink flange is undamaged and tight, with no signs of leakage, you can probably leave it in place. Chances are good that the mounting brackets on the new unit will fit just fine. To find out, remove the old disposal and install the new flange on it. If it fits, you can install the new disposal using the old flange.

Don't struggle with the snap ring

Weight down the sink flange

Tighten with pliers

Compare outlet heights

Spend a little more

You can buy a 1/3-hp disposal for $80 or less, but our experts suggest that a more expensive unit with at least 3/4 hp would be a better choice. The more powerful the motor, the less chance it will jam. In addition, higher-priced disposals are generally quieter and have longer warranties.

Silicone seals best

Inspect the plumbing first

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