Replacing an InSinkErator takes two to four hours and requires turning off power, draining the sink, and unbolting the old unit from underneath

You can replace an InSinkErator garbage disposal yourself if you are comfortable working under a sink with basic hand tools. The job involves disconnecting the old unit, removing it from the mounting ring, and installing a new one in its place. You will need to turn off the electrical power at your breaker box before you start, and you should have a bucket ready to catch water that drains from the pipes.

The hardest part is usually breaking loose the old mounting bolts, which can corrode or tighten over years of use. If you run into stuck bolts or damaged plumbing connections, you may want to call a plumber rather than risk cracking a pipe. Most people without plumbing experience can handle the straightforward swap, but know your limits before you start.

Key Takeaways

  • Turn off power at the breaker box and test the disposal to confirm it is dead before you touch anything.
  • You will need a bucket, adjustable wrench, screwdriver, and possibly a disposal wrench or pipe wrench to loosen the mounting bolts.
  • The old unit hangs from a mounting ring bolted to the sink drain; you remove the bolts from underneath the sink to drop it free.
  • The new InSinkErator slides into the same mounting ring if you are replacing with the same model, or you may need to install a new ring if you are switching brands.
  • Reconnect the drain pipes hand-tight first, then tighten them fully once you confirm the disposal sits level and centered.

What You Need Before You Start

Gather your tools and materials in one place so you do not have to hunt for them while you are under the sink. You will need an adjustable wrench (or a disposal wrench if you have one), a screwdriver, a bucket, and a flashlight or headlamp. Have towels or rags ready to soak up water that will spill when you disconnect the drain pipes.

Check whether your new InSinkErator is the same model as the old one. If it is, the mounting ring will match and installation is simpler. If you are switching to a different model or brand, you may need to buy a new mounting ring or adapter kit—ask the supplier when you purchase the new disposal. Have the new unit on hand before you start removing the old one, so you are not left without a sink drain while you wait for delivery.

Make sure the new disposal is the right horsepower for your home. Most residential units are 0.5 to 1 horsepower; check your circuit breaker to see what amperage the outlet is rated for. A 15-amp circuit can handle a 0.5 hp disposal, but a 1 hp disposal usually needs a 20-amp circuit. If your breaker is undersized, you will need an electrician to upgrade the circuit before you install the new unit.

Turn Off Power and Drain the Sink

Locate your home's electrical breaker box and find the breaker labeled for the garbage disposal. Switch it to the OFF position. Go back to the sink and flip the disposal switch to confirm it does not run—this is your safety check that power is truly off.

Fill the sink with a few inches of water, then open the cabinet doors under the sink and place a bucket underneath the drain pipes. Pull out the drain plug or stopper and let the water drain into the bucket. Once the water has stopped, you are ready to disconnect the pipes.

Disconnect the Drain Pipes

Look under the sink at the pipes connected to the disposal. You will see a large pipe coming from the sink drain (the tailpiece) and a smaller pipe going to the wall or floor (the trap arm). The disposal sits between these two connections.

Use your adjustable wrench to loosen the large nut where the tailpiece meets the disposal. Turn it counterclockwise until it is hand-tight, then unscrew it the rest of the way by hand. Water may still drip, so keep your bucket underneath. Next, loosen the nut where the trap arm connects to the disposal using the same method. Once both nuts are loose, you can wiggle the pipes free from the disposal.

If the nuts are stuck or corroded, spray them with penetrating oil (like WD-40) and wait 15 minutes before trying again. Do not force them—if they will not budge, stop and call a plumber rather than risk cracking the pipes.

Remove the Old Disposal from the Mounting Ring

The disposal hangs from a metal ring bolted to the underside of the sink drain. You will see three bolts around the ring, usually spaced evenly. Use your adjustable wrench or disposal wrench to loosen each bolt by turning counterclockwise. Work on one bolt at a time, loosening each a quarter turn, then go around again. This prevents the disposal from tilting and getting stuck.

Once all three bolts are loose enough, you can unscrew them by hand. Keep them in a safe place—you may reuse them for the new disposal if it is the same model. As the last bolt comes free, the disposal will drop slightly. Support it with one hand so it does not fall and hit the pipes below. Carefully lower the old disposal and set it aside.

Inspect the mounting ring for cracks or damage. If it looks intact, you can reuse it. If it is cracked or bent, you will need to replace it before installing the new disposal—this is a job for a plumber unless you are very comfortable with plumbing work.

Install the New Disposal

Before you lift the new disposal into place, check that the mounting ring is clean and free of old rubber gaskets or putty. Wipe it down with a dry cloth. If the new disposal came with a new gasket or seal, install it on the ring according to the manufacturer's instructions—this usually means pressing it firmly into the groove on the ring.

Lift the new disposal and align it with the mounting ring. The disposal should have a notch or alignment mark that lines up with a pin or mark on the ring. Slide the disposal up into the ring until it sits flush against the sink. Insert the three bolts and tighten them by hand first, then use your wrench to tighten them evenly. Again, work on one bolt at a time, a quarter turn at a time, so the disposal stays level and centered.

Do not over-tighten the bolts—snug is enough. Over-tightening can crack the ring or strip the bolts. Once all three bolts are snug, the disposal should not wiggle or move when you push on it.

Reconnect the Drain Pipes

Take the tailpiece (the pipe from the sink) and slide it onto the disposal outlet. Hand-tighten the large nut first, then use your wrench to tighten it fully. It should be snug but not so tight that you cannot loosen it later if you need to. Next, reconnect the trap arm (the pipe to the wall or floor) the same way.

Once both pipes are connected, fill the sink with water and turn the disposal on to check for leaks. Watch underneath for drips at the connection points. If you see water dripping, turn off the disposal and tighten the nut a bit more. If the leak continues after tightening, turn off the breaker and disconnect the pipe to check whether the gasket is seated properly.

If you see water leaking from inside the disposal itself (not at the connections), the disposal may be defective. Stop using it and contact the manufacturer or retailer about a replacement.

Test the New Disposal

Once the pipes are connected and you have confirmed there are no leaks, run the disposal for 30 seconds with cold water flowing. Listen for unusual noises—grinding and humming are normal, but rattling or grinding that sounds like metal on metal is not. Turn it off when ready if you hear anything wrong.

Run the disposal a few more times over the next day or two, watching for leaks each time. Check underneath the sink after each use. If everything stays dry and the disposal runs smoothly, the installation is complete.

Frequently Asked Questions

Do I need a plumber to replace a garbage disposal?

Not necessarily. If you are comfortable with basic hand tools and the old unit comes out easily, you can do it yourself. Call a plumber if the mounting bolts are stuck, the pipes are corroded or damaged, or you are not confident working under a sink with water and electrical connections nearby.

Can I install a different brand of disposal in the same mounting ring?

Sometimes, but not always. Different brands have different mounting systems. Check the new disposal's manual to see if it fits your existing ring, or ask the supplier before you buy. If it does not fit, you will need a new ring or adapter kit, which usually requires a plumber to install.

What if water leaks from the disposal after I install it?

Tighten the connection nuts a bit more first. If the leak continues, turn off the breaker and disconnect the pipe to check that the rubber gasket is seated properly in the groove. If the gasket is in place and the leak persists, the disposal may be defective and should be replaced under warranty.

How long does it take to replace a garbage disposal?

Two to four hours for most people doing it for the first time. If the old unit comes out easily and the pipes are in good condition, you might finish in two hours. If bolts are stuck or you run into unexpected plumbing issues, it can take longer.

Do I need to turn off the water to replace a garbage disposal?

No, but you should turn off the breaker at the electrical panel. Have a bucket ready to catch water that drains from the pipes when you disconnect them. You do not need to shut off the main water line.