How-To: Garbage Disposal Plumbing Installation: Easy Steps

Did your garbage disposal start making strange gurgling sounds then suddenly stop working altogether? Or maybe you just moved into a new home and want to install a new disposal. Either way, you’ve in the right place.

We’ll show you how garbage disposal installation can be quick and easy. All you need is some basic knowledge of home repairs and the right equipment.

You’ll also need a handy how-to guide, which you’ll find below. Take a look.


How to Install Your Garbage Disposal in 10 Easy Steps

Let’s roll up our sleeves and get started.

Step 1: Gather Your Supplies

Here’s what you’ll need:

  • Dishwasher drain connector kit
  • Phillips and flathead screwdrivers
  • Hammer
  • Pipe wrench
  • Plumber’s putty
  • Electrical connectors and clamps
  • A bucket

Step 2: Disconnect the Power and Water

The first step is disconnecting the power, which you can do from the circuit breaker or the fuse box. Next, turn off the water supply via the shutoff valve under the sink.

Then, use the wrench to disconnect the pipes below the sink. Have your bucket handy to catch any water.

Once the pipes are gone, push on the drain from below the sink. It’ll come right out. Wipe the sink with a clean cloth.

Step 3: Install the New Garbage Disposal Drain

Your new drain, or flange, should come with a rubber gasket. However, you can choose to place a layer of plumber’s putty instead of the gasket.

We should mention that many believe putty makes for a better, long-lasting seal than the gasket. Anyway, whichever sealant you decide on, make sure you press down on the drain to set it in place.

Step 4: Secure the Mounting Bracket

For this next step, you’ll need to keep the garbage disposal drain in place as you work below the sink. Either ask someone to hold it in place for you or place something heavy on the drain, like the disposal itself. To protect the sink from scratches, lay a towel between it and whatever object you decide to go with.

Next, slide the fiber gasket onto the drain sleeve beneath the drain, followed by the backup flange. Finally, use your screwdriver to tighten the fastening, or mounting, screws to the mounting bracket.

The best way to do this is to turn each screw a couple of turns at a time, alternating between each one. This ensures that the bracket and drain are effectively seated against the sink.

Bear in mind that, once you’re done, you may find excess putty around the drain. That’s perfectly fine. Simply, cut off the extra pieces using a sharp knife and throw them away.

Step 5: Attach the Discharge Tube

Start by attaching the rubber gasket to the tailpipe. This is the large opening on the side of the garbage disposal.

Next, look for a piece of short pipe with a 90-degree angle, known as the discharge tube. Then, take the metal fastening flange and slide it through the tube.

After that, you’re going to take the flared end of this tube and attach it to the rubber gasket you just installed on the tailpipe. Secure the tube in place using the two screws provided. They’ll help form a watertight seal between the discharge tube and the tailpipe.

Step 6: Prepare the Dishwasher Drain Hose Outlet

Above the tailpipe, you’ll find a smaller outlet closed shut via a knockout plug where the dishwasher drain hose will go.

To remove it, lay the disposal on its side. Then, using a hammer and a screwdriver, gently tap on it until it pops out and into the garbage disposal.

If you don’t have a dishwasher, you can keep the knockout plug in place.

Step 7: Connect the Wires

Garbage disposals are either hardwired or corded. If the garbage disposal comes with a factory-installed cord, then you’ve got it easy. All you have to do is plug the cord into the outlet located underneath your sink.

If the unit is hardwired, you’ll need to do a bit of electrical work. You’ll also need to buy some electrical cable connectors and a power cord kit.

Here are the basic steps to set up your hardwired garbage disposal and connect it to a cord. Before you start, make sure the circuit breaker is turned off.

  1. Turn the garbage disposal on its side to remove the electrical cover plate on the bottom.
  2. Pull out the wires.
  3. Using wire connectors, join wires from the disposal to their corresponding wires coming from the power supply.
  4. Tighten the connectors and gently push the wires back into the body of the disposal.
  5. Replace the cover plate and secure the power cord to the bottom of the unit via a clamp.

Step 8: Hang the Garbage Disposal

This step is the most challenging for some people because the disposal can get pretty heavy as you’re working below the sink. However, if you’re doing the garbage disposal installation alone, remember that slow and steady wins the race. It also reduces the risk of damage or injuries.

First, make sure the mounting tabs align with the slide-up ramps on the mounting ring you screwed in place in step three. There are three in all to ensure maximum stability of the unit.

Start by holding the garbage disposal in one hand. With the other, turn the lower mounting ring. Keep rotating it until all three tabs lock into place on the mounting framework.

Step 9: Connect the Garbage Disposal Drain to the P-Trap

Remember the discharge tube you attached to the disposal in step four? You’re going to connect it to the pipe underneath the sink.

Next, insert the discharge tube and slide the clamp up over it. The tube should now be positioned within the threads on the coupler on the p-trap, also called the drain trap. Make sure you tighten the clamp to prevent leaking.

If the tube is too long, cut off the extra length. On the other hand, if it’s too short, you can always buy an extension. Simply attach one end of the discharge tube and the other to the drain trap.

Step 10: Test Your New Garbage Disposal

Remember to turn the electrical breaker and the water supply back on. Then, run the water to check for leaks. If everything looks good, plug in the disposal and test it out.


Garbage disposals are a convenient addition to any kitchen. If you’re into DIY projects, then our how-to guide on garbage disposal installation should come in handy.

Just grab your tools, and you’re ready to go!