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How to Install a Garbage Disposal: Step-by-Step Instructions

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Installing a garbage disposal is a relatively easy task and something you can do yourself, especially if you're a DYI kind of person. We'll take you step-by-step thru the process with pictures and a video.

This article primarly covers installing a garbage disposal for the first time. Although, if you are replacing your disposal, you'll also find the information you need. If you don't have an electrical outlet under your sink, or a wall switch to turn the disposal on and off, you should contact a professional electrician before starting.

Preparing to Install a Garbage Disposal

Now that you've purchased your new garbage disposal you're probably excited to get it installed and running. It's important to keep safety top of mind since you'll be working with water and an electrical appliance. Take your time, and if you don't feel comfortable, you should contact a professional plumber.


One thing to keep in mind is that each garbage disposal is slightly different from the next. You should always refer to your disposal's installation instructions, as it'll have the most accurate information for your specific unit.

Supplies You'll Need to Replace Your Garbage Disposal

Garbage Disposal Replacement

If you're replacing a garbage disposal, follow these steps and then jump to Step 3:

  • Disconnect the drain trap from the discharge tube.
  • If you have a dishwasher, disconnect the dishwasher attachment.
  • Insert a screwdriver to the right of 1 of the 3 mounting lugs on the mounting ring.
  • Turn the screwdriver counter clockwise (left) to release the disposal from the mounting ring. Be prepared and hold onto the disposal. Once it's released, it will fall. 
  • Remove the disposal's electrical plate and disconnect the wiring.
  • If you are replacing the disposal with a similar model, you may be able to use the existing mounting assembly.
  • If not, you'll need to detach the mounting assembly by removing the snap ring. Once the snap ring is removed, the entire mounting assemby will come off the sink flange.
  • Use a screw driver to loosen the nut holding the sink flange in place.
  • Remove the sink flange from the top.

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How to Install a Garbage Disposal

One thing to keep in mind is that each garbage disposal is slightly different from the next. You should always refer to your disposal's installation instructions, as it'll have the most accurate information for your specific unit.

Turn OFF the Electricity - Before you start, it's critical that you turn OFF the circuit breaker in your home's electrical panel.

Disconnect the drain line

Step 1

Disconnect The Drain Pipe

  • Place a bucket under the drain pipe to catch any water that may be in the pipes.
  • Disconnect the drain pipe. Depending on your set-up, you may need to use a pipe wrench.
Remove the sink strainer

Step 2

Remove Sink Strainer

  • Remove the sink flange from the sink's drain hole. You should be able to pull it out easily. Although, you can use a screw driver or putty knife to pry under the edge if necessary.
Putty knife scraping away excess  putty

Step 3

Remove Excess Putty

  • Using your putty knife, scrap away any excess putty left of the sink opening.
  • Use a towel to clean the sink opening and surrounding area.
Applying a rope of plumbers putty onto the flange

Step 4

Putty Around Flange

  • Grab a handful of plumbers putty and role it between your hands until it forms a rope that is between 1/2 to 3/4 inches thick. 
  • Apply the rope of plumbers putty around the new flange.
  • The plumbers putty needs to fully surround the flange. Add more if needed.
  • Press the flange into place making sure that any writing on the flange is straight and facing you.
  • As you press the flange into the sink opening, the plumbers putty will seep out from the sides. This is normal and does not need to be removed at this time. 
  • The plumbers putty will prevent the sink flange from leaking.
Garbage disposal on towel inside sink

Step 5

Secure Flange from Moving

  • Place a towel inside the sink and on top of the flange.
  • Set the garbage disposal on top of the towel. This will keep the flange from moving while you're working underneath.
Prepare mounting bracket

Step 6

Prepare the Mounting Ring

  • Stack the fiber gasket, on top of the backup flange. Then place the mounting ring (with the 3 bolts) on the bottom. It's often easiest to loosen the mounting ring bolts. 
  • Find the metal snap ring and have it within reach.
Install mounting ring to sink flange

Step 7

Install Mounting Bracket

  • Working under the sink, you'll likely see a small amount of plumbers putty seeping between the sink flange and the sink. This is okay and does not need to be removed. 
  • Install the fiber gasket, backup flange and mounting ring under the flange.
  • You can install these components as a group as the video shows, or you can put them in place one piece at a time. Just make sure that they are in the correct order. The smooth side of the backup flange should be against the sink.
  • Position one side of the snap ring over the groove on the bottom of the sink flange and pull the other side open. The ring should snap into place.
  • Double check that the snap ring is seated correctly within the groove.  
Tighten bolts to secure the mounting ring

Step 8

Secure Into Place

  • Tighten the bolts evenly by alternating from one bolt to another until they are against the back-up flange.
  • It's a good idea to check that the sink flange hasn't moved while you are tightening the bolts. Simply remove the garbage disposal from the sink and check that the writing is still facing you.
  • The back-up flange should be tightly seated to the sink.
Clean excess putty from sink flange

Step 9

Clean Sink Drain

  • Remove the garbage disposal and towel from inside the sink.
  • Use your putty knife and clean-up any excess putty from the sink flange.
Hammer and screw driver knocking out drain plug

Step 10

Remove Drain Plug

Only do this step if you HAVE a dishwasher

  • Set the disposal on a firm surface, such as a counter or floor. 
  • Locate the dishwasher knock out plug. 
  • Place a screw driver in the center of the drain plug and, using a hammer, knock out the plug.
  • Find and remove the plastic plug from the inside of your garbage disposal. 
Connect the electrical wires from the disposal to the cord

Step 11

Connect Wiring

  • Turn the disposal upside down and locate the wiring plate on the bottom.
  • Remove the wire cover plate with a screw driver and gently pull the black and white wires out.
  • You'll also see a green screw. This is the ground.
  • Screw a 3/8" Clamp Connector into place on the bottom of the disposal. Typically there's a hole for the connector next to the wiring plate. Purchase the appropriate cord for your disposal, if a cord did not come with your unit. Or, if you prefer, you can hard wire the disposal instead of using a cord.
  • Slide the cord into the clamp connector from the top. Be sure to leave enough room to make a connection.
  • Use wire strippers to expose a small amount of wire.
  • The wire that has green (often in the casing) or is bare without a casing, will go with the green screw. Twist the exposed wire and carefully wrap it around the green screw; then tighten the screw so that the wire will not slip.
  • Match the disposal's wire colors to the electrical cord wires. White-to-white / black-to-black. Sometimes the black wire will be a different color, such as red or blue.
  • Twist the white wires together in a clockwise direction with a pair of plyers. Then use wire nuts on the twisted wires. Twist the wire nuts clockwise until they are snug. There should not be any exposed wire. Repeat with the black wires.
  • Gently put the wires back into the garbage disposal and replace the wire cover plate.
  • Tighten the screws on the cord clamp connector until they are snug.

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Placing gasket within the discharge connection

Step 12

Insert Discharge Gasket

  • Locate the discharge tube on the disposal. 
  • Place the gasket within the discharge outlet.
Connecting the discharge tube with the flange

Step 13

Connect Discharge Tube

  • Connect the discharge tube to the discharge outlet.
  • Use the discharge flange and bolts to secure the tube into place. Again, evenly tighten the screws. 
  • Depending on where your sink trap is located, it may be necessary to use a hacksaw and cut the discharge tube down to size. Or use an adapter to length. It's a good practice to measure this first, before mounting  the disposal.
Position the garbage disposal under the sink

Step 14

Connect the Disposal

  • Position the disposal into place under the sink. 
  • Align the 3 tabs on the disposal to the 3 openings on the mounting ring. Then turn until the mount is holding the disposal.
  • Use the included wrench or a screw driver to tighten and secure the disposal in place.
  • Now you can rotate the disposal so that the discharge tube aligns with the drain pipe. 
Attach the dishwasher drain to the garbage disposal

Step 15

Connect Dishwasher Drain

  • Connect the dishwasher drain to the disposal's dishwasher drain outlet.
  • Secure the drain line with a hose clamp to prevent it from slipping off.
Align discharge pipe with under sink plumbing

Step 16

Align the Discharge Pipe

  • Check that the discharge pipe is properly aligned with your plumbing.
  • Connect the disposal's discharge pipe to your sink's drain pipe.
  • In some cases, it may be necessary to reconfigure the drain.
Check plumbing for leaks

Step 17

Check for Leaks

  • Turn the water ON in the sink. Place the stopper into the sink drain.
  • Check for leaks at the sink flange, mounting assembly, tail pipe, and dishwasher connections. 
  • If there are no leaks, plug in the disposal.
  • Turn ON the circuit breaker in your home's electrical box, and  test your garbage disposal.

Watch the Full Video

As you can see, installing a garbage disposal isn't difficult, but you will need to work with plumbing and electricity. If you're not comfortable taking on this project, you should contact a professional plumber.


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