The Homeowner’s Guide to Garbage Disposal Installation

Whether you're replacing the old garbage disposal or installing one for the first time, your life is about to change, and you can thank John W. Hammes (the guy who invented garbage disposals) for it.  If you've been limping along with a broken disposal, or none at all,  you can go back to the luxury of grinding up your food waste in no time at all.

The big question most homeowners ask when buying any new appliance is this: can it be a DIY project, or should I call a professional?

We have great news! If you're handy, you can likely handle garbage disposal installation on your own. The guide below will walk you through the steps.

First Things First

If you've done even just a few home improvement projects, you know how vital it is to have the right tools for the job. Here are the primary tools and materials you'll need:

  • Channel Lock Pliers
  • Flat-Head Screwdriver
  • Hammer
  • Plumber's Putty
  • Putty Knife
  • Bucket
  • Flashlight

Tip: Most manufacturers supply an instruction sheet with a list of necessary tools. They should also include the mounting bracket and hardware.

A Few Safety Precautions

Anytime you repair or replace an electrical appliance, you must shut off the power before you start working. If you're replacing the disposal, unplug it and turn off the power to the garbage disposal at the main circuit-breaker box.

If you haven't labeled the circuits on the box, it's easy enough to flip each circuit breaker until you locate the one for the garbage disposal. One thing you might find when you go to turn off the power is that your garbage disposal and dishwasher sometimes share the same circuit.

Prepare to Remove the Old Disposal

Removing the existing disposal isn't tricky, but there are few steps to follow. If your current disposal connects to the dishwasher, you'll need to remove the pipe that connects the disposal to the dishwasher. You'll have to loosen the clamp and remove the hose first.

Before you disconnect and remove the pipe, make sure you've placed a bucket underneath. The bucket catches any remaining wastewater from the pipes.

Next, grab your channel locks and remove the fittings on the p-trap (the pipe is a u-shape). Allow the water to drain into your bucket.

Once you've drained all the water, you can move on to removing the disposal.

Next Steps to Removal

First, determine whether you can unscrew the unit from the sink drain. If not, your disposal likely has a snap ring that you'll pry open with your screwdriver.

Be careful to hold onto the garbage disposal from the bottom while you're removing it. You'll find out that it's quite heavy!

Now, you can remove the old mounting assembly. It's an excellent time to have your flashlight handy so that you can see the screws you'll need to loosen.

Locate three screws and the two rings they support. One ring fits in the groove on your sink sleeve. Remove it first, and then the sink sleeve, gasket, and drain flange.

Don't forget to clean up the area around the sink opening – old plumber's putty, sealing gaskets, and any other debris you can see or feel.

Tip: If you're replacing the old disposal with an identical model, you can reuse the mounting assembly.

How to Install the Mounting Assembly and Drain Flange

This next step applies to DIYers who are either starting from scratch or installing a completely different model than the one they've just removed. The drain flange (also called the sink flange) comes first!

Grab your plumber's putty, roll it out like a snake, and place a ¼-inch line around the drain. Place the drain flange into the drain and push it down slowly onto the plumber's putty.

Now, you can install the gasket and mounting ring by pushing them up the flange. Connect the snap ring directly to the flange, which holds the ring and gasket in place.

Time to Tighten the Mounting Bolts

Find the three mounting bolts on the assembly and start tightening them, one at a time. You want to make sure you tighten them evenly.

Don't panic if you notice putty oozing out from under the flange. Use your putty knife and remove the excess.

Garbage Disposal Wiring 101

You're almost there! If your disposal comes with a power cord, great! If not, you must remove the cover plate on the disposal so that you can get to the wiring.

Find your power supply and connect the white and black wires on the disposal to the coordinating wires on the power supply. Then, ground the supply wire. Remember to put the electrical covers back on.

If you're not entirely comfortable working with wiring or electrical connections, don't hesitate to contact a qualified plumbing professional to come out and help with the install.

Mounting the New Unit

Your next step is mounting the disposal by aligning the rubber ring on the top part of the disposal with the drain flange. Once you have the disposal in place, you should secure it loosely.

Once you have the unit secured, you can rotate the disposal until you've aligned it with the drain assembly. This step is critical, and you'll want to make sure the discharge outlet on the disposal sits directly in front of the drain pipe connection.

What About the Plumbing?

You've already lined up the discharge tube with the drain pipe. Keep in mind that it may not align perfectly, even if the one you just removed did.

You may need to cut some PVC pipe to make the proper connection. Once you have the plumbing connected, tighten all the nuts and the rotating collar on the mounting assembly.

Checking Your Work

You're almost ready to flip the switch and start grinding up some food waste, but first, check your work. Don't turn the power back on just yet, but do turn on the faucets.

Look for any areas where you might have water leaking. Also, if you have a dishwasher, and you've connected the disposal to it, turn it on so that you can check for water leaks there.

If you do notice leaks, you can go back and tighten up things without too much fuss. Once you've made sure you have tight connections, you can turn the power back on and plug in your new disposal!

Need Help with Garbage Disposal Installation?

There's nothing like a home improvement project that comes together seamlessly. If you've looked at our guide and the instruction manual for your new garbage disposal and decided you'd rather have someone else do the job, don't hesitate to call a plumbing professional.

Our team is ready to help with your garbage disposal installation or any other plumbing service you need. Contact us today to schedule a visit.

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