What You Need Before You Start

Installing a Moen garbage disposal is a plumbing job you can do yourself if you are comfortable working under a sink and have basic tools. The process takes two to four hours and involves disconnecting the old unit (if there is one), mounting the new Moen disposal, and reconnecting the drain lines and electrical cord. You will need a screwdriver, adjustable wrench, plumber's putty, and a flashlight. Have a bucket ready—water will spill.

Before you buy, check that your sink has a disposal outlet. If you are replacing an old unit, you can reuse the existing mounting hardware. If you are installing in a sink that has never had a disposal, you will need to cut a hole in the sink strainer basket, which requires a knockout kit (Moen sells these separately). Turn off the circuit breaker that controls the outlet under your sink, or if there is no dedicated outlet, you will need to have an electrician install one—this is not a DIY step.

Read the instruction sheet that comes with your specific Moen model before you start. Different Moen disposals have slightly different mounting systems, and the manual will show you exactly which parts go where.

Key Takeaways

  • Turn off power at the circuit breaker before you touch any wiring or the old disposal unit.
  • The mounting ring screws onto the sink strainer basket from underneath, and the disposal hangs from that ring using a bayonet or threaded collar depending on your Moen model.
  • Drain lines must slope downward toward the main drain line, or water will pool and cause odors and clogs.
  • If you do not have an outlet under the sink, or if the old outlet is damaged, stop and call a licensed electrician—do not extend a cord across the floor or use an adapter.

Remove the Old Disposal (If You Have One)

Turn off the circuit breaker for the outlet under the sink. Flip the switch on the wall to confirm the power is off, then try to run the disposal—it should not turn on. Unplug the cord from the outlet.

Place a bucket under the drain connection to catch water. Use an adjustable wrench to loosen the slip nut that connects the drain line to the disposal outlet. Turn it counterclockwise by hand once it is loose enough. Disconnect the dishwasher hose if one is attached (it screws onto a port on the side of the disposal).

The disposal hangs from a mounting ring that is screwed onto the sink strainer basket. Look underneath the sink and locate the three mounting bolts that hold the ring in place. Loosen all three bolts by turning them counterclockwise with a screwdriver. The disposal will drop into your hands—support it as you loosen the last bolt so it does not fall. Set it aside.

Install the Mounting Ring and Strainer Basket

If you are reusing the old mounting ring, skip to the next section. If you are installing a new ring (because you are putting a disposal in a sink for the first time, or the old ring is damaged), you need to remove the old strainer basket first. Loosen the large nut underneath the sink that holds the basket in place, then push the basket up and out from the top of the sink.

Clean the sink opening and the underside of the sink around the hole. Roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the new strainer basket rim. Push the basket down through the sink hole from the top. From underneath, thread the rubber washer and metal washer onto the threaded post, then hand-tighten the large nut. Use a wrench to tighten it firmly—do not over-tighten, or you will crack the sink.

Screw the mounting ring onto the threaded post of the strainer basket. The ring should sit flat against the underside of the sink. If it does not, the strainer basket is not tight enough. Tighten the large nut a bit more and try again.

Hang the New Moen Disposal on the Ring

Check your Moen manual to see whether your model uses a bayonet mount or a threaded collar. Most newer Moen disposals use a bayonet system: the disposal has three tabs on its upper rim that align with three slots in the mounting ring. Hold the disposal up to the ring, align the tabs with the slots, and push the disposal up and to the right (or left—your manual will specify). You will hear or feel a click when it locks in place.

If your model uses a threaded collar, you will screw the collar onto the threaded post of the mounting ring by hand, then tighten it with a wrench. Do not over-tighten—hand-tight plus a quarter turn with a wrench is enough.

Once the disposal is mounted, it should hang securely and not wiggle. If it does wiggle, the mounting ring is not tight enough on the strainer basket. Tighten the large nut under the sink a bit more.

Connect the Drain Lines

The drain line from the sink connects to the outlet port on the side of the disposal. If you removed an old disposal, you can reuse the old slip nut and rubber washer. If you are installing new, use the parts that came with the Moen unit.

Slide the slip nut onto the drain line, then the rubber washer. Push the drain line onto the outlet port of the disposal and hand-tighten the slip nut. Use an adjustable wrench to tighten it another half turn. It should be snug but not so tight that you strip the threads.

If you have a dishwasher, the hose connects to a port on the side of the disposal. This port is usually capped with a rubber plug. Pop the plug out with a screwdriver and screw the dishwasher hose onto the port. Tighten it by hand plus a quarter turn with a wrench.

The outlet of the disposal connects to the main drain line (the line that goes to the wall or floor). This connection should slope downward at least a quarter inch per foot of pipe. If the old line is level or slopes upward, water will pool in the pipe and cause clogs and odors. Adjust the position of the disposal or the drain line to create the proper slope, then tighten all connections.

Plug In and Test

Once all drain lines are connected and tight, turn the circuit breaker back on. Flip the wall switch to confirm the disposal turns on. Let it run for a few seconds, then turn it off. Fill the sink with a few inches of water and turn the disposal on again. Water should drain smoothly without backing up into the sink.

Check under the sink for leaks at the slip nuts and the strainer basket. If you see water dripping, turn off the disposal and tighten the leaking connection a bit more. Wipe up any water that spilled during installation.

Run the disposal one more time with the water on to make sure everything is working. If the disposal makes a grinding noise that sounds like metal on metal, turn it off when ready and check for a foreign object inside. If it hums but does not turn, the motor may be jammed—do not force it. Call a plumber if the disposal does not work after installation.

When to Call a Plumber

Stop and call a licensed plumber if you do not have an outlet under the sink, or if the existing outlet is damaged or does not work. Installing a new outlet requires a licensed electrician and is not a DIY job. Do not use an extension cord or adapter to power the disposal.

If you are not comfortable working with plumbing connections, or if your sink has an unusual configuration (pedestal sink, very shallow cabinet, or a sink with a garbage disposal already installed in one bowl and you are adding one to the other), a plumber can install the disposal in a few hours and will warranty the work. The cost is usually between $200 and $400 for labor, depending on your area and the complexity of the job.

Frequently Asked Questions

Do I need a special outlet for a Moen garbage disposal?

Yes. The outlet should be a standard 120-volt, 15-amp outlet located under the sink, and it should be on a dedicated circuit (meaning nothing else plugs into it). If you do not have one, an electrician will need to install it. Do not use an extension cord or power strip.

Can I install a Moen disposal if I have a septic system?

Most septic systems can handle a garbage disposal, but check your septic tank manual or ask your septic service provider first. Disposals that grind food very finely (like Moen models) are generally safer for septic systems than older models, but you should still avoid putting fibrous foods, grease, or large quantities of food waste down the drain.

What if water backs up into the sink after I install the disposal?

The drain line may not be sloped correctly, or the connection to the main drain line may be too tight or blocked. Turn off the disposal and check that the drain line slopes downward. Loosen the slip nut at the main drain connection and see if water flows freely. If it does not, the main drain line may be clogged—you will need a plumber with a drain snake to clear it.

How tight should I make the slip nuts?

Hand-tight plus a quarter to half turn with a wrench. If you over-tighten, you can strip the threads and cause a leak that is harder to fix. If you under-tighten, the connection will leak. Start loose and tighten gradually until the leak stops.

Can I install a Moen disposal myself if I have never done plumbing before?

Yes, if you are comfortable with basic tools and following written instructions. The hardest part is usually getting the mounting ring tight enough on the strainer basket. Take your time, read the manual twice, and do not force anything. If you get stuck, a plumber can finish the job for you.