Step-by-Step Guide to Installing a Garbage Disposal

Installing a garbage disposal can be a straightforward DIY project that helps keep your kitchen efficient and tidy. Whether you’re replacing an old unit or installing a new one, this step-by-step guide will walk you through the process, saving you money on professional installation fees.

When to Replace Your Garbage Disposal

While repairs can address some issues, there are times when replacing your garbage disposal is the better choice. Here are a few indicators that it might be time for an upgrade:

Upgrading for capacity: If your current disposal (e.g., a ⅓-hp model) struggles to keep up with increased food waste from frequent home cooking or a growing family, consider upgrading to a higher horsepower model.
Frequent reset button use: The reset button, located on the bottom of most disposals, is designed to restart the motor after it overheats. If you find yourself resetting it regularly, this may indicate the motor is overworked and a replacement is due.
Old age and persistent issues: Garbage disposals generally have a lifespan of around 10 years. If yours is nearing or beyond this age and needs constant repairs, replacing it may be more cost-effective.

Tools You’ll Need for Installation

Gather the following tools and materials before starting:

New garbage disposal and mounting hardware
Plumber’s putty
Phillips and flathead screwdrivers
Nut drivers (⅜-inch and 5/16-inch)
Hammer or mallet
Needle nose pliers
Towel
Work gloves

How to Install a Garbage Disposal

Follow these steps to properly install a garbage disposal and ensure it operates correctly.

Turning Off Power

Turn off all circuit breakers connected to the disposal to prevent any power from reaching it.
Confirm there is no power going to the disposal or wiring before starting.

Gathering Materials

Verify that your new garbage disposal includes all necessary components, such as the mounting assembly.
If a power cord is not included, purchase a compatible one.
Gather additional tools, including wire cutters/strippers, wire nuts, and strain relief, as needed.

Disassembling Mounting Assembly

If the mounting assembly is pre-assembled, disassemble it to prepare for installation.
Loosen or loosely thread the screws on the mounting ring.

Preparing the Workspace

Clear out the area under the sink by removing the old garbage disposal, mounting assembly, and flange.
Clean the sink flange area to remove any residue from the previous installation.

Applying and Installing the Sink Flange

Roll a ½-inch rope of plumber’s putty and apply it evenly around the new sink flange.
Press the sink flange firmly into the sink opening, leaving the excess putty for later cleanup.

Assembling the Mounting Hardware

Slide the fiber washer into place beneath the sink.
Position the backup flange with its lip facing downward.
Attach the mounting ring with screws loosely threaded.
Secure the snap ring by holding the mounting ring in place, fixing one side of the snap ring, and snapping it into place with a flathead screwdriver.
Tighten the screws on the mounting ring to create a secure seal for the flange.

Cleaning Up Excess Putty

Remove any excess putty from the sink after tightening the mounting ring.

Removing the Knockout Plug (if connecting a dishwasher)

Lay the disposal on its side.
Use a flathead screwdriver and hammer to knock out the knockout plug.
Remove the plug from inside the disposal using needle-nose pliers.

Wiring the Disposal

Lay the disposal upside down on a towel.
Remove the access plate using a Phillips screwdriver.
Pull out the internal wires and strip the ends of the power cord wires by ½ inch, if not pre-stripped.
Feed the power cord wires through the strain relief hole and pull them into the access opening with needle-nose pliers.
Connect the neutral wire (likely white) from the power cord to the disposal’s neutral wire using a wire nut.
Connect the smooth wire (likely black) to the disposal’s power wire.
Attach the grounding wire (likely green) to the grounding screw and tighten it securely.
Leave slack in the power cord and tighten the strain relief.
Tuck the wires back into the disposal and replace the access cover.

Installing the Gasket and Discharge Tube

Press the gasket into place in the discharge hookup by hand.
Slide the diamond-shaped flange onto the discharge tube.
Seat the tube and flange, then tighten the bolts with a nut driver.

Installing the Disposal Under the Sink

Lift the disposal into position under the sink, aligning it with the mounting ring.
Align the three locking tabs on the disposal with the sink-side mounting ring.
Turn the mounting ring counterclockwise by hand to engage the tabs.
Use the included tool to fully tighten the mounting ring.

Aligning and Connecting Plumbing

Rotate the disposal to align it with the plumbing connections.
Adjust or trim the discharge tube as needed.
Attach the discharge tube to the straight pipe.
Connect the dishwasher hose, if applicable, to the knockout fitting and tighten the clamp with a 5/16-inch nut driver.

Testing for Leaks

Plug the sink with the disposal stopper and turn on the water to fill the sink.
Check under the sink for leaks around the flange and mounting hardware.
If there are no leaks, plug in the disposal or flip the circuit breaker back on.

Testing Operation

Remove the stopper from the sink and let the water drain.
Check for leaks in the tubing or disposal as the water drains.
Turn on the disposal to confirm that it is running correctly.

Common Mistakes to Avoid During Installation

Installing a garbage disposal can go smoothly if you avoid these common pitfalls:

Incorrect size selection: Buying a disposal that doesn’t fit the space under your sink can delay the installation process.
Skipping a gasket check: Forgetting to install or properly secure gaskets can lead to leaks.
Tightening mounting hardware unevenly: This can cause the unit to wobble, leading to noise and potential damage.
Ignoring plumbing compatibility: Some disposals require specific plumbing connections that might not match your current setup.
Overlooking power requirements: Not all disposals plug directly into a power outlet; some require hardwiring.
Forgetting to knock out the dishwasher plug: If connecting a dishwasher, failing to remove the plug inside the disposal’s inlet can cause drainage issues.

Maintenance Tips for a Long-Lasting Garbage Disposal

Keeping your garbage disposal in good working condition is essential for longevity and performance. Follow these tips:

Run water while using it: Always run cold water before, during, and after use to flush waste properly.
Avoid hard items: Limit what goes into the disposal—avoid bones, fruit pits, or fibrous foods like celery that can jam the unit.
Clean regularly: Use ice cubes and salt to clean the blades and remove buildup, or grind citrus peels for a fresh scent.
Avoid harsh chemicals: Skip drain cleaners, as they can corrode parts of the disposal. Use a natural cleaning solution instead.
Inspect connections: Check the mounting assembly and drain connections periodically for wear or leaks.
Use it regularly: Frequent use helps prevent rust and keeps moving parts in good condition.

In Summary

That’s everything you need to know to install a garbage disposal! If you’ve been hesitant about taking on this task, think of it as a manageable way to upgrade your kitchen while saving money. It’s a step-by-step process, and with a little time and effort, you can handle it yourself.

With this guide in hand, you’re equipped to handle the installation and enjoy the satisfaction of completing a hands-on project. A smoother kitchen workflow is just a few steps away!

Step-by-Step Guide to Installing a Garbage Disposal