You can replace an InSinkErator garbage disposal yourself if you are comfortable working under a sink and have basic tools

Replacing an InSinkErator takes two to four hours for most people and costs between $150 and $400 for the unit itself, depending on the model. The work involves disconnecting the old disposal, unbolting it from the sink, installing the new one in reverse order, and reconnecting the plumbing. You do not need a plumber unless the mounting ring is stuck, the drain line is damaged, or you are not confident working with electrical connections.

The hardest part is usually removing the old unit — the mounting ring can corrode or tighten over years of use. Once that comes free, the rest is straightforward: fit the new disposal into the mounting assembly, tighten the bolts, reconnect the drain and electrical lines, and test it.

Key Takeaways

  • Turn off power at the breaker and test the outlet with a voltage detector before you touch anything electrical.
  • The mounting ring holds the disposal to the sink; you will need a screwdriver or hex wrench to loosen the three bolts underneath it.
  • Drain lines and electrical connections come off the old unit and go onto the new one in the same configuration.
  • Most InSinkErator models use a standard mounting assembly, so a replacement disposal from any brand will fit if the sink flange is intact.

What you need before you start

Gather these tools and materials: a flathead screwdriver, a hex wrench or Allen key (usually 1/4 inch), a bucket or towel to catch water, a voltage detector or multimeter, plumber's putty, and a new InSinkErator disposal unit. Check your old unit's model number — it is stamped on the side or bottom — so you can buy a replacement with similar horsepower and features. A 1/2 horsepower model is standard for most homes; 3/4 horsepower handles tougher jobs but costs more.

You may also need a new rubber gasket and mounting ring if the old ones are cracked or warped. These come with most new disposals, but if your sink flange is damaged, you will need a replacement flange kit — this is when calling a plumber becomes worth the cost.

How to disconnect the old disposal

Turn off the circuit breaker that controls the disposal outlet. Use a voltage detector to confirm the power is off by touching it to the outlet — it should show no current. This step is not optional; a disposal can still spin if power is live, and your hand can be in the way.

Unplug the disposal from the outlet under the sink. If it is hardwired (connected directly to the electrical box with no plug), you will need to disconnect the wires inside the junction box. Turn off the breaker first, then loosen the wire nuts and separate the black, white, and ground wires. Take a photo before you disconnect them so you know which wire goes where on the new unit.

Place a bucket under the drain line where it connects to the disposal. Loosen the hose clamp with a screwdriver and slide the drain line off. Water will spill, so have a towel ready. If the line is glued on with plumber's putty, you may need to cut it or pry it gently with a flathead screwdriver.

Removing the mounting ring and old disposal

Look under the sink at the mounting ring — the metal collar that holds the disposal to the sink flange. You will see three bolts spaced evenly around it. Use a hex wrench or screwdriver to loosen all three bolts. Turn each one counterclockwise a quarter turn, then move to the next one, and repeat until they are all loose enough to unscrew by hand.

Once the bolts are out, the disposal will drop. Support it with one hand while you work, or it will fall into the cabinet. Twist the disposal slightly side to side as you lower it — the mounting ring may be stuck to the sink flange. If it will not budge, spray penetrating oil around the ring, wait 15 minutes, and try again. Do not force it or you risk cracking the sink.

Once the old disposal is out, scrape off the old putty and rubber gasket from the sink flange with a flathead screwdriver. Wipe the flange clean with a damp cloth and let it dry completely. If the flange is cracked or the threads are stripped, you will need a new flange kit — this requires removing the sink itself and is a job for a plumber.

Installing the new disposal

Roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the sink flange. This seals the gap between the sink and the mounting ring. Place the rubber gasket on top of the putty, then slide the new mounting ring up through it. The ring should sit flush against the sink from below.

Insert the three bolts through the mounting ring and hand-tighten them. Then use your hex wrench to tighten each bolt in a star pattern — tighten one, skip one, tighten the next — so the ring pulls up evenly. Tighten until the ring is snug against the sink, but do not over-tighten or you will crack the sink. The bolts should feel firm, not rock-hard.

Slide the new disposal up into the mounting ring. It will click or lock into place when it is seated correctly. Twist it gently to confirm it is find. If it spins freely, it is not locked in; lift it out and reseat it.

Reconnecting the drain and power

Slide the drain line back onto the outlet port of the disposal and tighten the hose clamp. If the line is cracked or leaking, replace it with a new one — they cost $10 to $20 and are easier to swap now than later. Make sure the clamp is tight enough that the line does not slip off under water pressure, but not so tight that you crush the plastic.

Reconnect the electrical lines. If the disposal has a plug, straightforward plug it into the outlet. If it is hardwired, match the wires to your photo: black to black, white to white, and bare copper or green to ground. Twist each pair together, screw a wire nut onto each connection, and tuck the wires back into the junction box. Screw the cover plate back on and turn the breaker back on.

Testing and troubleshooting

Fill the sink with a few inches of water. Turn on the disposal and let it run for 10 seconds, then turn it off. Listen for unusual grinding or rattling — a new disposal should sound smooth and quiet. Check under the sink for leaks at the drain connection and around the mounting ring. If water drips from the drain line, tighten the hose clamp another quarter turn.

If the disposal does not turn on, check that the outlet has power by plugging in a lamp. If the lamp works but the disposal does not, the disposal may have a reset button on the bottom — press it and try again. If it still does not work, the unit may be defective and you should return it.

If water leaks from around the mounting ring, the putty seal may not be tight. You will need to remove the disposal, scrape out the old putty, and reseal it. This is rare if you tightened the bolts evenly, but it can happen if the sink flange was not clean before you started.

When to call a plumber instead

Call a plumber if the mounting ring will not come loose after you have sprayed it with penetrating oil and waited. Forcing it risks cracking the sink or stripping the threads on the flange. A plumber has tools to remove stuck rings without damage.

Also call a plumber if the drain line is glued to the old disposal with epoxy or if the sink flange is cracked, warped, or missing threads. These problems require work above the sink or replacement parts that are easier to handle with professional tools. A plumber visit costs $100 to $200, but it is cheaper than replacing a sink.

If you are not comfortable working with electrical connections, especially if the disposal is hardwired, a plumber can handle that part for you. You can still remove the old unit and prepare the sink yourself to save on labor.

Frequently Asked Questions

Can I install a different brand of disposal in place of my InSinkErator?

Yes. Most disposals use the same standard mounting assembly, so a Waste King, Badger, or Moen disposal will fit in the same space. Check that the new unit has the same horsepower or higher — a 1/2 horsepower unit will fit where a 1/2 horsepower InSinkErator was, but you cannot put a 1/3 horsepower unit in that space because the mounting ring will not align. The drain and electrical connections are the same across brands.

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

No, but you should turn off the breaker and unplug the disposal before you touch it. Water will spill when you disconnect the drain line, so have a bucket ready. You do not need to shut off the main water supply unless the drain line is damaged and you want to avoid water damage while you work.

How long does a new InSinkErator disposal last?

Most disposals last 8 to 15 years with normal use. InSinkErator units tend to last toward the longer end of that range because they are built with heavier motors and thicker grinding chambers. Lifespan depends on how often you use it and what you put down it — grinding bones and fibrous vegetables shortens the life, while grinding soft food scraps extends it.

What should I do if the disposal leaks after I install it?

Check the hose clamp on the drain line first — tighten it another quarter turn. If water is leaking from around the mounting ring where it meets the sink, the putty seal is not tight. Remove the disposal, scrape out the old putty, clean the flange, explore new putty, and reinstall. Leaks from the disposal body itself mean the unit is defective and should be returned.

Can I replace a disposal if my sink does not have a garbage disposal outlet?

No. Installing a disposal in a sink that was not designed for one requires cutting a hole in the sink, installing a new flange, and running electrical to that location. This is a major renovation and requires a plumber and possibly an electrician. It is not a DIY replacement job.