What you need to do before you start

Replacing an InSinkErator garbage disposal is a job you can do yourself if you are comfortable working under a sink and handling basic plumbing connections. The disposal itself usually comes out in under an hour, and the new one goes in about the same time. You will need a few tools — a screwdriver, an adjustable wrench, a bucket, and possibly a flashlight — but no special equipment.

Before you touch anything, turn off the power to the disposal at the circuit breaker. Flip the switch to the off position and leave it there. Do not rely on the wall switch alone; someone could turn it on while you are working. If you are not sure which breaker controls the disposal, turn it on, then flip breakers one at a time until it stops. Mark that breaker with tape so you know which one it is.

Place a bucket under the sink to catch water that will spill when you disconnect the drain lines. Even if the sink is empty, there is always some water sitting in the pipes. Have towels ready as well.

Key Takeaways

  • Turn off power at the circuit breaker before you start, and leave it off until the job is completely finished.
  • The disposal is held in place by a mounting ring that twists counterclockwise; once you remove it, the unit drops out of the sink opening.
  • You will need to disconnect the drain line and the dishwasher line (if your disposal has one) before the old unit comes free.
  • The new disposal mounts the same way the old one did, and you can reuse the same drain connections if they are not cracked or leaking.
  • After installation, run water and test the disposal before you consider the job done.

How to remove the old disposal

Look under the sink at the disposal unit. You will see a large metal ring at the top where the disposal connects to the sink opening. This is the mounting ring. Using your adjustable wrench or a large screwdriver, turn this ring counterclockwise. It will take some force — it is meant to stay tight. Once it loosens, you can usually finish turning it by hand. The disposal will drop down once the ring is completely off.

Before the unit falls out, you need to disconnect the drain line. This is the pipe that runs from the bottom of the disposal to the main drain under the sink. It is usually held on with a large slip nut — a nut that tightens by hand around the pipe. Loosen this nut by turning it counterclockwise. Water will pour out, which is why you have the bucket underneath. Once the nut is loose enough, you can unscrew it the rest of the way by hand and pull the drain line free.

If your disposal has a dishwasher line — a smaller hose that runs from the dishwasher to the side of the disposal — disconnect that as well. It is usually held on with a hose clamp. Loosen the clamp with a screwdriver and slide the hose off. Now the old disposal is free and you can pull it out and set it aside.

Preparing the sink opening for the new unit

With the old disposal out, look at the sink opening. You will see the mounting ring assembly still in place. Some people replace this assembly with a new one when they install a new disposal; others reuse the old one if it is not damaged. Check the rubber gasket — the rubber ring that sits between the sink and the mounting assembly. If it is cracked, dried out, or falling apart, replace the entire mounting assembly. If it looks intact and flexible, you can reuse it.

If you are reusing the old assembly, clean it thoroughly. Wipe away any old putty, food debris, or mineral buildup. If you are installing a new mounting assembly, remove the old one completely. Most disposals come with a new assembly in the box, or you can order one separately from InSinkErator. Follow the instructions that come with your new disposal for how to install the mounting assembly — the steps vary slightly between models.

Installing the new disposal

Before you lift the new disposal into place, check that the power is still off at the breaker. Lift the new unit up to the sink opening and align it with the mounting ring. The disposal will have a groove or slot that matches a corresponding piece on the mounting ring. Line these up and push the disposal up into the opening.

Once the disposal is seated in the opening, you will turn the mounting ring clockwise to lock it in place. This is the reverse of how you removed the old one. Turn the ring by hand first, then use your wrench to tighten it firmly. Do not over-tighten — you want it snug, not stripped. The disposal should not move or rattle when you push on it.

Reconnecting the drain and dishwasher lines

Now reconnect the drain line. The slip nut goes back on the threaded part at the bottom of the disposal. Hand-tighten it first, then use your wrench to snug it down. It should be tight enough that water does not leak, but again, do not strip the threads by over-tightening. If the old drain line is cracked or the connection leaks when you test it later, you will need to replace it with a new one.

If there is a dishwasher line, reconnect it to the side of the disposal. Slide the hose onto the port and tighten the hose clamp with a screwdriver. Make sure the clamp is snug so the hose does not slip off when the dishwasher runs.

Testing the new disposal before you finish

Before you consider the job done, turn the power back on at the circuit breaker. Fill the sink with a few inches of water, then flip the wall switch to turn on the disposal. Let it run for a few seconds while the water drains. Listen for any unusual grinding or rattling sounds, and watch under the sink for leaks at the drain connection and the dishwasher line.

If water is leaking from the slip nut at the drain, turn off the disposal and tighten the nut a bit more. If it still leaks, the threads may be damaged and you will need a new drain line. If water is leaking from the dishwasher line connection, tighten the hose clamp. If the disposal sounds normal and there are no leaks, the job is complete.

When to call a plumber instead

If the mounting ring will not come loose, or if you strip the threads while trying to remove it, stop and call a plumber. Forcing it can damage the sink itself. If the drain line is cracked or the threads are damaged, you can replace just the line without removing the disposal — a plumber can do this quickly if you are not comfortable doing it yourself.

If you turn on the new disposal and it does not run at all, check that the power is on at the breaker and that the wall switch is in the on position. If it still does not run, the unit may be defective and you should contact InSinkErator or the retailer where you bought it. Do not take the disposal apart to troubleshoot — return it for a replacement.

Frequently Asked Questions

Can I install a different brand of disposal in the same sink opening?

Yes. Most disposals use the same standard mounting assembly, so a Moen, Waste King, or other brand will fit in the same opening where your InSinkErator was. You may need to buy a new mounting ring if the one in your sink is damaged, but the opening itself does not change.

What if the disposal is stuck and I cannot turn the mounting ring?

Try spraying the ring with penetrating oil and waiting 15 minutes for it to soak in. Then try again with your wrench. If it still will not budge, stop — forcing it can crack the sink. Call a plumber at this point; they have tools to remove stuck rings without damaging the sink.

Do I need to replace the drain line when I install a new disposal?

Not necessarily. If the old line is not cracked and the connection does not leak when you test the new disposal, you can reuse it. If it leaks or is visibly damaged, replace it with a new one that matches the diameter of the old one.

Can I install a disposal if I do not have a dishwasher?

Yes. The dishwasher line is optional. If you do not have a dishwasher, you straightforward do not connect anything to that port on the disposal. Some disposals come with a plug for that port; if yours does not, you can buy one separately.

How long does a new InSinkErator disposal usually last?

Most disposals last 8 to 15 years depending on how often you use it and what you put down it. Avoid putting fibrous foods, bones, or grease down the disposal, as these wear out the motor faster and can jam the blades.