How to Replace a Garbage Disposal: Steps, Wiring and Safety

How to replace a garbage disposal: switch off the power at the breaker and confirm it is dead, disconnect the drain pipe and dishwasher hose, unplug or unwire the old unit and twist it off its mounting ring, fit the new mount if needed, hang and wire the new disposal, reconnect the drain and test for leaks.

It is a manageable DIY job if you are careful with power and water.

How to replace a garbage disposal: before you start

Check that the new unit fits your sink flange and trap layout. Many disposals use a standard three-bolt mounting system, but brands differ. Read the instructions that come with yours, because wiring and mounting details vary, and check local rules about electrical work.

Quick facts: how to replace a garbage disposal
Time	About 1 to 2 hours
Tools	Screwdrivers, adjustable pliers, bucket, flashlight, hex key, plumber's putty if the kit needs it
Power	Breaker off; test that it is dead; never rely on the wall switch
Call a plumber or electrician if	Wiring is unclear, the flange is damaged or the drain does not line up

Step by step

1. Turn off the breaker for the disposal and test the wires or plug with a voltage tester. Unplug the unit if it has a cord.
2. Place a bucket under the trap and disconnect the drain pipe and the dishwasher hose. Food water will spill out.
3. Support the old disposal with one hand and turn the mounting ring so it drops free. Lower it and set it aside.
4. Disconnect the wiring by removing the cover plate under the unit and noting how the wires connect. Photograph it first.
5. Check the mounting assembly. If the sink flange, gasket or snap ring is worn, replace it using the new kit and plumber's putty as the instructions say.
6. Knock out the dishwasher plug if you connect a dishwasher. Remove the plug from the inlet with a hammer and screwdriver, then retrieve it from inside.
7. Wire the new disposal to match: black to black, white to white, green or bare to the ground screw. Close the plate.
8. Hang the unit by lifting it to the mounting ring and turning it until it locks. Reconnect the discharge pipe and the dishwasher hose, then tighten the clamps.
9. Restore power, run water and test. Check every connection for drips while it runs.

Common wiring set-ups

Set-up	What to do
Plug-in cord	Plug into the outlet under the sink after the unit is mounted
Hardwired	Connect wires inside a junction box using wire nuts; consider an electrician
New cord kit	Install per the kit instructions, using a proper cord grip

Mistakes that cause leaks

Forgetting the gasket, overtightening and cracking the flange, leaving the dishwasher knockout plug in place so the dishwasher cannot drain, and cross-threading the discharge pipe all cause trouble. Tighten parts firmly but not violently, and run water for several minutes while you watch the joints.

Choosing a replacement

Match the horsepower to how you use it, and check the noise, the feed type and the warranty. A continuous-feed model is the usual choice for homes. Check the flange fit and whether your kitchen has an outlet or a hard-wired connection.

Safety

Never put a hand in the chamber. Keep water away from open wiring. If you are not sure the circuit is off, stop and call an electrician. Wear eye protection, because old debris and water spray out when you disconnect pipes.

When to call a professional

If the sink flange is cracked, the pipes do not line up, the wiring is not what you expect or the unit leaks after you try twice, a plumber can finish the job quickly. Knowing how to replace a garbage disposal helps you decide whether it is worth doing yourself.

How to replace a garbage disposal: plan the swap

Before you start, turn off the power at the breaker and confirm the unit is dead with a tester. Knowing how to replace a garbage disposal well starts with the mounting: most units lock onto the sink flange with a snap ring that turns counterclockwise. Support the old unit as you release it, then disconnect the drain pipe, the dishwasher hose if there is one, and the wiring. Buy a replacement with the same mounting type. Set the new flange with plumber's putty, then tighten the mounting screws evenly. A leaking connection after a swap is usually a loose slip nut or a gasket that was not seated, so check every joint with a dry towel before you run water.

Learning how to replace a garbage disposal is easier with a helper who can hold the unit while you turn the snap ring. Once you know how to replace a garbage disposal, keep the mounting instructions with the new unit for future reference.

Before the new unit goes in, dry-fit it and confirm how to replace a garbage disposal will leave room for the drain connection.

Related reading

• Garbage Disposal Not Working? Reset, Unjam and Test It
• How to Reset a Garbage Disposal: Button, Hex Key and Power
• How to Clean a Garbage Disposal: Ice, Salt, Citrus and Brush
• Dishwasher Water Backing Up Into Sink: Causes and Fixes

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