When and why you need to replace your garbage disposal

A garbage disposal typically lasts 8 to 15 years before it stops working well enough to replace. You'll know it's time when the unit jams constantly even after you clear the drain, leaks water from the bottom or sides, makes grinding noises that don't stop, or straightforward won't turn on no matter what you do. Once a disposal reaches this point, repair parts are often as expensive as a new unit, and a new one will run more efficiently.

Replacement is a task many homeowners can do themselves if you're comfortable working with plumbing connections and electrical wiring. The job takes 30 minutes to an hour once you have the new unit. If you're not confident with either plumbing or electrical work, calling a plumber is the safer choice—they'll handle it correctly and carry insurance if something goes wrong.

Key Takeaways

  • Turn off the power at the breaker before you start, and do not skip this step—garbage disposals are electrical and can cause serious injury.
  • You'll need a new disposal unit, a wrench, a screwdriver, plumber's putty, and possibly a new mounting ring if your current one is corroded.
  • The old unit disconnects from three places: the sink flange at the top, the drain pipe below, and the electrical outlet underneath.
  • The new unit installs in reverse order, and you must seal the sink flange with plumber's putty to prevent leaks.
  • If you're unsure about the electrical connection or drain plumbing, stop and call a plumber rather than guessing.

What you'll need before you start

Gather these tools and materials before you begin: a new garbage disposal unit (check your sink's mounting type and power requirements first), an adjustable wrench, a screwdriver (usually Phillips head), plumber's putty, a bucket or towel to catch water, and a flashlight. You may also need a putty knife to scrape old putty away.

If your current disposal has a three-prong plug that goes into an outlet under the sink, you won't need an electrician. If it's hardwired directly into the electrical system (no plug visible), stop here and call a plumber—that requires a licensed electrician to disconnect and reconnect safely. Check your current setup before you buy a new unit, because some disposals are plug-in and others are hardwired, and they're not interchangeable without rewiring.

Turn off power and disconnect the old unit

Go to your home's electrical panel and flip the breaker that controls the garbage disposal. If you're not sure which one it is, flip the breaker and have someone test the disposal by pressing the switch—nothing should happen. Leave the breaker off the entire time you're working. This is not optional; it prevents electrocution.

Place a bucket under the drain pipe below the disposal to catch any standing water. Loosen the large nut that connects the drain pipe to the bottom of the disposal using your wrench, then unscrew it by hand. The pipe will come loose and water may drip out—that's normal. Next, locate the mounting ring (the metal collar that holds the disposal to the sink flange above) and loosen the three bolts around it using your wrench. The old disposal will drop down into your hand once these bolts are loose enough.

If your disposal has a plug, unplug it from the outlet under the sink. If it's hardwired, you should not have reached this point—call a plumber. Once the disposal is free, set it aside.

Remove the old sink flange and prepare the opening

Look up into the sink opening where the disposal was mounted. You'll see a metal ring (the sink flange) that's sealed to the underside of the sink with old plumber's putty. Use a putty knife to scrape away as much of this old putty as you can. Work from underneath the sink, scraping around the entire flange until the putty is mostly gone and the flange is loose enough to wiggle.

Once the putty is removed, the flange should lift out from above. If it's stuck, tap it gently from below with a rubber mallet or the handle of your wrench. Clean the sink opening thoroughly—any old putty left behind will prevent a good seal on the new unit. Wipe the area with a damp cloth and let it dry completely before you install the new flange.

Install the new disposal unit

Take the new disposal out of the box and check that it comes with a new mounting ring and sink flange. If your old mounting ring is in good condition and not corroded, you can reuse it, but most people replace it with the new one that comes in the box. Insert the new sink flange into the opening from above, pushing it down until it sits flush with the sink surface.

From underneath the sink, roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the flange where it meets the sink. This seal prevents water from leaking down into the cabinet. Screw the new mounting ring up onto the flange bolts from below, tightening the three bolts evenly in a star pattern (tighten one, skip one, tighten the next) so the flange sits level. Don't over-tighten—snug is enough.

Hang the new disposal unit onto the mounting ring by aligning the three tabs on the disposal with the slots on the ring, then twist it clockwise until it locks into place. You should hear or feel a click. Reconnect the drain pipe by screwing the large nut back onto the bottom of the disposal by hand first, then tightening it with your wrench until it's snug but not over-tight.

Reconnect power and test

If your new disposal has a plug, plug it into the outlet under the sink. If it's hardwired, stop and call an electrician—do not attempt this yourself. Go back to your electrical panel and flip the breaker back on. Return to the sink and press the disposal switch. It should run smoothly without grinding or rattling. Let it run for 10 seconds, then turn it off.

Run water into the sink while the disposal is off to check for leaks around the flange and drain connection. Look underneath the sink with your flashlight. If water is dripping from the flange seal, turn off the disposal and tighten the mounting ring bolts a bit more. If water is leaking from the drain pipe connection, tighten that nut slightly. Small drips that stop after a few seconds are normal as the system settles. If water continues to pour out, turn off the water and tighten the connection more.

Once everything is dry, run the disposal again with water flowing for 15 seconds to make sure it operates normally. If it jams, turns off, or makes unusual noises, turn it off when ready and check for debris in the drain or a loose connection.

When to call a plumber instead

Stop the project and call a plumber if: the disposal is hardwired rather than plug-in; you're uncomfortable working with plumbing connections; water leaks continue after you've tightened all connections; the new disposal doesn't fit your mounting system; or you damage the sink flange or drain pipe during removal. A plumber will finish the job correctly and handle any complications that come up.

The cost of a service call plus installation is usually $150 to $300 depending on your area, but that's far cheaper than water damage under your sink or an electrical hazard. If you're renting, check your lease before you replace anything—your landlord may require a licensed plumber to do the work.

Frequently Asked Questions

Can I replace a garbage disposal myself if I've never done plumbing before?

Yes, if the disposal is plug-in and you follow each step carefully. The plumbing connections are straightforward hand-tightened nuts. The main risk is electrical—never skip turning off the breaker. If you're unsure at any point, stop and call a plumber rather than guessing.

What's the difference between a plug-in and hardwired disposal?

A plug-in disposal has a three-prong cord that plugs into an outlet under the sink, like a toaster. A hardwired disposal is connected directly to your home's electrical wiring and requires an electrician to disconnect and reconnect. Check under your sink before you buy a replacement.

How tight should I make the bolts on the mounting ring?

Snug is enough—tight enough that the flange doesn't wiggle, but not so tight that you're straining. Over-tightening can crack the sink or strip the bolts. If you're tightening with a wrench and it suddenly gets much easier, you've gone too far and may have stripped the bolt.

What if water leaks from under the sink after I install the new disposal?

Check two places: the flange seal (where the sink meets the disposal) and the drain pipe connection. Tighten the mounting ring bolts slightly if water is coming from the flange. Tighten the drain pipe nut if water is leaking there. Small drips that stop after a few seconds are normal. If tightening doesn't stop the leak, call a plumber.

Do I need to replace the mounting ring, or can I reuse the old one?

You can reuse it if it's not corroded or damaged. Most new disposals come with a new ring, and using it is simpler because everything is designed to fit together. If your old ring is in good shape and you want to save money, it will work fine.