How to Replace a Garbage Disposal

Updated: Apr. 16, 2024

Need to know how to install a garbage disposal? Our step-by-step garbage disposal installation guide makes it super quick and easy!

Time

1 - 2 hours

Complexity

Beginner

Cost

$101–250

Introduction

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.

Tools Required

Hacksaw
Hammer
Hex wrench
Pliers
Screwdriver

Materials Required

New garbage disposal
Plumber's putty
Silicone

Like most power equipment, garbage disposals don’t last forever, so those noises coming from your unit might be trying to tell you something. On average, garbage disposals last between 10 and 15 years, and over that time, the blades get dull and the moving parts just function as well as they did when it was first installed.

Fortunately, replacing a garbage disposal is a pretty straightforward DIY task that’s a reasonable project for most beginners. Here, we’ll show you how to remove your old one and replace it with a new unit.

When to replace a garbage disposal

Timing is an obvious factor here. If it’s been a dozen years or more since your garbage disposal was installed, it could be time to replace it. There are other signs to look for besides the odd hums and unusual grinding. Other signs to look out for include frequent clogging, leaks, power issues or if you’re having to reset the unit often.

When to call a pro

Don’t be intimidated by replacing a garbage disposal. It’s not hard, and in most cases, you won’t need anything more than a very rudimentary understanding of how plumbing works. I replaced the garbage disposal in my house in 2023, and it took me less than two hours. The old one was struggling with even the most basic waste and making noises that sounded like they were recorded for a horror flick. In my case, it was pretty straightforward; I didn’t even have to adjust the size of the discharge tube.

However, if you’re uncomfortable working with plumbing or if you notice unusual leaking under your sink, it might be best to call a professional plumber or a general contractor. Installing a garbage disposal where there wasn’t one before is a more complicated task that could require some electrical work, like adding an outlet under the sink, which could require hiring a pro.

Project step-by-step (7)

Step 1

Remove the old garbage disposal

How to remove a garbage disposal

Disconnect the power. In most cases, there’s an outlet under the sink that the disposal is plugged into. If you have a hardwired disposal, turn off the breaker that controls it.
Turn off the water supply to the sink. This step will prevent someone from turning on the sink while you have the disposal and drain pipes disconnected.
Disconnect the discharge tube and the dishwasher drain.
Remove the disposal from the mounting unit.
- Tip: These things are heavy, so we’ve found it helpful to have support underneath the old unit before you remove it from the flange. You can use a paint can and some wood scraps, like we’ve done here, so something similar. Just leave a 1/2-in. gap so there’s room to remove it from your makeshift stand.

Replace a Garbage Disposal anatomy of the garbage disposal

Step 2

Install garbage disposal mounting hardware

You can skip this step if your new disposal fits with the old mounting assembly. To check, take the old unit you just removed and see if it fits with the mounting bracket that came with the new one. If that’s the case, skip to the next step. If not, read on.
Remove the mounting assembly and sink flange.
- Loosen the mounting screws and pry off the snap ring. The best way to do that is to slide the blade of a flathead screwdriver between the ring and flange, starting at the break in the ring. Pull down on the ring with the screwdriver’s blade and walk the blade around the ring. The ring should pop right off.
- Remove the old sink flange. Be sure to scrape off the old putty too.
With everything removed and cleaned up, you’re ready to install the new sink flange and mounting bracket. Start by adding a 1/2-in. bead of plumber’s putty around the drain opening in the sink. Drop in the new flange and press it down. Once it’s in place, you can use the old disposal unit as a weight to keep it in place while you assemble the parts underneath. Just put a towel down first so you don’t scratch your sink.
Moving to underneath the sink, slide the gasket, backup flange and upper mounting bracket over the bottom of the sink flange. Then, slip the snap ring into the grove on the bottom of the sink flange and tighten the screws on the mounting ring.

Step 3

Remove the dishwasher knockout plug

If you’re connecting the new disposal to a dishwasher, you’ll have to remove the knockout plug from the inlet where the dishwasher drain attaches to the unit.

Use a hammer and screwdriver to tap the plug until it falls out. It’s just a small plastic disc, but you’ll want to reach into the unit and remove it before installing it. You don’t want a chuck of plastic to be the first thing that your brand new disposal tries to grind up!

Step 4

Connect the power cord to the new garbage disposal

If you new garbage disposal did not come with a pre-installed power cord (most models do not) you’ll have to attach one. You have the option of using the power cord from your old disposal, which will save you a few bucks.

Remove the cover plate on the bottom of the unit. Match the colored wires on the disposal with the ones on the power cord and connect them with wire nuts. Connect the grounding wire over the green screw and tighten it.
Reattach the cover plate.

Replace a Garbage Disposal don't forget the cord Family Handyman

Step 5

Mount the new garbage disposal

Align the three mounting tabs with the mounting ring. Use the wrench that came with the new unit (or a screwdriver) to turn the tabs and lock it into place.
- When you mount the new disposal, make sure the outlet faces the drain pipe.

Step 6

Connect the discharge tube and dishwasher drain

Attach the gasket and the discharge tube to the garbage disposal and tighten the screws. Then, connect the discharge tube to the sink drain and tighten the connection.
- You may need to adjust the length of the discharge tube for the new disposal. If it’s too long, simply connect it to the disposal, mark it and cut it with a hacksaw for your garbage disposal installation. (Loosen the other pipe connections, if necessary, to insert the tube back into the tee.) If the old discharge tube is too short, you’ll have to get a new one.
Next, connect the dishwasher line, if you have one.

Replace a Garbage Disposal prepare for a new discharge tube

Step 7

Test the garbage disposal

Plug in the new unit and turn the breaker on again.
Turn on the water faucet and let it run for a few minutes to test for any leaks under the sink. If you notice any, make sure all the connections are tight.
With the water running, turn on the disposal and make sure it’s running smoothly. You can even take it for a trial run with a few food scraps.

FAQs

How much does a new garbage disposal cost

On average, you can expect to pay between $150 to $200 for a new 1/2- to 3/4-horsepower garbage disposal. You can buy a 1/3-hp disposal for less than $100, but the best garbage disposals have at least 3/4 hp, which is the optimal size for a three to four person household.. The more powerful the motor, the less chance it will jam. In addition, higher-priced disposals are generally quieter and have longer warranties.

How much does it cost to install a garbage disposal?

If you hire a plumber to do it for you, you can expect to pay anywhere from $400 to $1,000, depending on the market.

How long does a garbage disposal last?

A garbage disposal will usually last around 10-15 years, if you take care of it.

How do you clean a garbage disposal?

It’s pretty easy to clean a garbage disposal. There are several methods, but the easiest that we’ve found is using a mixture of baking soda and vinegar with a few drops of lemon essential oil.

How do you get smells out of your garbage disposal?

The same baking soda and vinegar concoction mentioned above will get rid of most smells in your garbage disposal.

What can go down a garbage disposal?

Soft foods and liquids are fine for garbage disposals. The important thing to remember is not to try to feed it too much at once. I once tried to run my garbage disposal after peeling a pound of carrots and it clogged up the discharge tube. Feed it smaller portions at a time.

What can’t you put down a garbage disposal?

Animal fats, grease and oils are right at the top of the list of things you should never put down a garbage disposal. They can congeal and cause a clog in your pipes. Coffee grounds can form clumps that will gum up the line. Pits from fruits and seeds are bad for the disposal too. Also avoid bones, shells, and stringy vegetables like celery. Don’t put paint down there either.