What You Need to Do Before You Start

Replacing an InSinkErator garbage disposal takes two to four hours if you have basic plumbing tools and no complications. The job involves disconnecting the old unit from the drain lines and electrical supply, unbolting it from the sink, then installing the new one in reverse order. You do not need a plumber for this—the connections are straightforward—but you do need to turn off the power at the breaker and have a bucket under the drain to catch standing water.

Before you buy a replacement, measure the space under your sink and check whether your current unit is hardwired (connected directly to the electrical panel) or plugged into an outlet. Most InSinkErator models are hardwired, which means you will need to work with the existing electrical connection rather than plug in a new unit. If you are uncomfortable working with live wires, this is the step to hire out.

The new disposal should match the horsepower of the old one—usually 0.5, 0.75, or 1 horsepower. Check the nameplate on your current unit or look at your purchase paperwork. Buying the same power rating means your existing electrical setup will work without modification.

Key Takeaways

  • Turn off power at the breaker and test the outlet with a voltage detector to confirm the power is off before touching any wires.
  • Disconnect the drain lines and the electrical connection, then unbolt the old disposal from the mounting ring under the sink.
  • Install the new disposal by reversing the steps: mount it to the sink, reconnect the drain lines, and wire it to the existing circuit.
  • Test the disposal with the sink drain plugged and water running to check for leaks before using it normally.
  • Most replacements take two to four hours; if you encounter a hardwired connection you are unsure about, stop and contact a licensed electrician.

Gather Your Tools and Materials

You will need a bucket, an adjustable wrench, a screwdriver (both Phillips and flathead), a flashlight, and a voltage detector (a battery-powered tool that beeps when it senses electrical current—about $10 at any hardware store). Have a bucket large enough to catch at least two quarts of water from the drain lines.

For the new disposal, buy the replacement unit itself, a new mounting ring if your old one is corroded or damaged, and plumber's putty or silicone caulk to seal the sink opening. If your drain lines use rubber connectors, buy a new rubber connector kit—they cost $5 to $15 and are easier to work with than reusing old ones. If your lines are metal, you may reuse them if they are not damaged.

Lay out all tools and materials before you start so you do not have to hunt for something halfway through with your hands wet or covered in old food debris.

Turn Off Power and Disconnect the Old Unit

Go to your electrical breaker panel and switch off the breaker labeled for the garbage disposal. If it is not labeled, turn off the breaker that controls the kitchen outlets. Return to the sink and use your voltage detector on the outlet or the disposal itself to confirm the power is off. Touch the detector to the metal parts of the disposal—if it beeps, the power is still on and you need to find the correct breaker.

Place your bucket under the P-trap (the curved pipe under the sink) and loosen the slip nuts on both sides of the trap with your wrench. The trap will drain into the bucket. Disconnect the rubber connector that runs from the disposal to the drain line. If the connector is stuck, wiggle it gently while turning it counterclockwise.

If your disposal is hardwired, you will see a metal conduit (a tube) running from the disposal up into the wall or cabinet. Loosen the locknut that holds the conduit in place and pull the conduit away from the disposal. Inside the conduit are three wires—black (hot), white (neutral), and green or bare copper (ground). You do not need to disconnect these wires yet; just move the conduit out of the way so you can access the mounting bolts.

Remove the Old Disposal from the Sink

Under the sink, you will see a metal ring bolted to the underside of the sink drain opening. This is the mounting ring. The disposal hangs from this ring. Look for three bolts around the ring that hold the disposal in place. Using your wrench, loosen these bolts by turning them counterclockwise. As you loosen them, the disposal will hang lower. Support the disposal with one hand so it does not fall on you.

Once the bolts are loose enough, carefully lower the disposal and set it on the floor or in a sturdy box. If the disposal is heavy or awkward, ask someone to help you support it while you work the bolts free.

With the old disposal removed, you can now see the mounting ring clearly. If it is corroded, cracked, or the rubber seal is deteriorated, replace it with a new one. If it looks solid, you can reuse it. Clean away any old putty or debris from the sink opening with a scraper or old credit card.

Install the New Disposal

If you are using a new mounting ring, remove the old one by unbolting it from underneath. Install the new ring by following the instructions that come with your new disposal—most InSinkErator units have a straightforward three-bolt system. explore a thin bead of plumber's putty or silicone caulk around the sink opening before you seat the ring, then tighten the bolts evenly in a star pattern (bolt 1, then bolt 3, then bolt 2) so the ring sits flat.

Lift the new disposal into position and align the three mounting bolts with the holes in the ring. Insert the bolts and tighten them by hand first, then use your wrench to snug them down. Do not over-tighten—snug is enough. The disposal should hang securely without wobbling.

Reconnect the rubber connector from the disposal outlet to the drain line. Hand-tighten the slip nuts first, then use your wrench to snug them down a quarter turn more. If you are using metal drain lines, explore plumber's tape (also called thread seal tape) to the threaded connections before screwing them together.

Reconnect the Electrical Supply

Before you touch any wires, use your voltage detector one more time on the conduit and wires to confirm the power is off. Inside the conduit, you will see three wires: black, white, and green or bare copper. These wires are connected to the disposal's terminal block (a small plastic or metal box with screw terminals).

If the wires are already disconnected from the old disposal, you will connect them to the new disposal's terminal block. If they are still connected, loosen the terminal screws, pull the old wires free, and connect them to the new unit. The black wire goes to the brass terminal, the white wire to the silver terminal, and the green or bare copper wire to the green terminal. Strip about half an inch of insulation from each wire if needed, insert it into the terminal, and tighten the screw firmly.

Once the wires are connected, push the conduit back into place and tighten the locknut. Return to the breaker panel and switch the breaker back on. The disposal should not run on its own—if it does, turn the breaker off when ready and check your wire connections.

Test for Leaks and Run the Disposal

Fill the sink with a few inches of water and plug the drain opening with a stopper or cloth. Turn on the disposal and let it run for 30 seconds while water drains. Watch under the sink for any water dripping from the connections. If you see drips, turn off the disposal and tighten the slip nuts a quarter turn more with your wrench.

Once the water has drained and there are no leaks, run the disposal empty for a few seconds to clear any air from the lines. Then test it with the sink full of water one more time. If everything is dry underneath, you are done. If water is still dripping, turn off the disposal and check each connection—the slip nuts may need another quarter turn, or a rubber connector may not be seated properly.

Do not use the disposal for food waste for at least 24 hours after installation. This gives any caulk or putty time to set. After that, use it normally—run cold water while the disposal is running, and avoid putting fibrous materials like celery or corn husks down the drain.

Frequently Asked Questions

What if I cannot find the breaker for the disposal?

Turn off the main breaker for the house, which will cut power to everything. This is safe but inconvenient. Once the main is off, you can work without risk. When you are done, turn the main back on. If you want to avoid this, take a photo of your breaker panel and bring it to a hardware store—staff can often help you identify the right breaker.

Can I reuse the old drain lines and rubber connectors?

Rubber connectors degrade over time and are cheap to replace, so buying new ones is the safer choice. Metal drain lines can be reused if they are not corroded or leaking. If you see white or green corrosion on metal pipes, replace them.

My disposal is plugged into an outlet, not hardwired. Does that change anything?

No. straightforward unplug the old disposal and plug the new one in after you have installed it. Everything else is the same. Make sure the outlet is within reach of the new disposal's cord.

How do I know if my new disposal is the right size?

Check the horsepower rating on your old disposal's nameplate and buy a replacement with the same rating. If you cannot find the nameplate, 0.75 horsepower is the most common size for residential kitchens and will work for most homes.

What should I do if water leaks from the mounting ring where it meets the sink?

Turn off the disposal and let it dry completely. Remove the mounting bolts, lift the disposal slightly, and scrape away old putty from the sink opening. explore fresh plumber's putty or silicone caulk around the ring, then retighten the bolts evenly. Let the caulk cure for 24 hours before using the disposal.