How to Replace a Garbage Disposal

By: Debbie Wolfe

Garbage disposals are designed to shred food and other waste into small bits so they can easily pass through  pipes and drains. They’re sturdy appliances, typically lasting between eight and 15 years. However, they can occasionally wear out before that time frame depending on how much use they get.

Signs you need a new garbage disposal

Look for these signs that your disposer drain is ready for replacement:

  • Odd noises—A garbage disposal has many moving parts, so any peculiar or new noises may be an indicator of a serious problem.
  • Persistent odors—Most odors will resolve on their own without any cleaning action. If the smell doesn’t dissipate after a rinse, there could be a problem with your disposal.
  • Frequent resets—If you’re hitting the reset button often, your garbage disposal may be aging out or have loose wiring.
  • Clogs—An occasional clog is normal with a garbage disposal, but frequent clogs are an indication that your garbage disposal is not up to par.
  • Leaks—If you discover water leaks or pools of water underneath your disposal, it’s time to swap it out. 
  • No power—Garbage disposals that don’t power on is a telltale sign that it’s time for a replacement. 

Fortunately, replacing a garbage disposal is a straightforward project that most DIYers can tackle in an afternoon without the need of a professional plumber.

Troubleshooting a garbage disposal

Before you replace your garbage disposal, check it thoroughly to see if it really needs to be replaced. Often, repairing your garbage disposal is more cost-effective than completely replacing it. Here are some common issues that should be examined before you buy a new garbage disposal:

  • Clear the jam—When you turn on the disposal and hear a grinding noise but see no movement, you most likely have a jam. To clear the jam, turn off the main power to the disposal and use a flashlight to visually inspect the inside of the unit. If nothing is visible, you might need to manually turn your blades to break up any clogged material. Note: never reach down a garbage disposal with your bare hands. 
  • Test the power—Sometimes, a broken garbage disposal may just be because the power is turned off. Verify that your disposal is plugged in and that an unplugged disposal is not the culprit. 
  • Press the reset button—If your garbage disposal is plugged in and still not running, press the reset button found on the bottom of the unit. If the reset button has tripped, it will be popped out. 
  • Check the circuit breaker—If resetting your garbage disposal doesn’t work, head to you circuit wall panel. Check to see if there’s a blown fuse or if the circuit breaker is tripped.
  • Inspect the switch—Once you’ve ensured the circuit breaker is all good, you could be dealing with faulty wires which may be causing the unit to short circuit. Shut off the main power going to the garbage disposal. Disassemble the switch control and inspect the wire connections. If the connections look loose, tighten them. Reassemble the switch and turn the power back on to test it. If it’s still not working, it may be time to call in a professional or replace the unit.

Garbage disposal replacement cost

The average cost to install a garbage disposal is between $20 and $40 per hour for labor, plus the cost of a new unit and other supplies. On average, new units range from $170 to $220.

Types of garbage disposals

There are two basic types of garbage disposals: continuous feed and batch feed. Both units are available for purchase at most big box home improvement stores and online.

  • Continuous feed—These common and easy-to-use units are open-mouth disposals that turn on and off with a wall switch. They require minimal maintenance and are simple to clean. They’re also more affordable than their batch feed counterparts.
  • Batch feed—These units are more expensive than continuous feed disposals. With this type of disposal, a stopper has to be placed into its opening before it can be activated. The stopper is what triggers the switch and turns on the motor.

Step-by-step guide to replacing a garbage disposal

Before installing a new garbage disposal, gather the necessary materials and remember to never stick your hands down a garbage disposal drain. It should take less than three hours to install a garbage disposal.

Materials

  • Hacksaw
  • Hammer
  • Hex wrench
  • Pipe wrench
  • Pliers
  • Screwdriver
  • New garbage disposal
  • Plumber putty
  • Garbage disposal power cord
  • Paper towels

Prep work

  1. Assemble the new unit—Piece together the new unit according to the manufacturer’s directions.
  2. Shut off the power—Garbage disposals have live electrical currents running through them, so shut off the power running to the unit from your home’s main circuit breaker.
  3. Shut off the water—Turn off the hot and cold water shut-off valves located in the cabinet under the sink and set a bucket under the P-trap to catch any dripping water.

Disassemble the existing unit

  1. Disconnect the discharge tube—Look for a drain pipe extending from the side of the unit that connects to the ground plumbing. Loosen the fasteners at the connection with a screwdriver and disconnect the tube and slip fittings to the drain. If your unit is connected to the dishwasher drain, you can disconnect the inlet hose in the same manner. 
  2. Remove a garbage disposal from its mounting assembly—Place a paint can or wood scraps underneath the unit for support. At the top of the disposal there will be a thin metal ring with three separate lugs. Firmly grasp up on the lugs and rotate the ring counterclockwise to remove the disposal.
  3. Disconnect electrical connections—Look underneath the unit to find the electrical cover plate. Unscrew the cover plate with a screwdriver and disconnect the wire connectors. Pull out the wire nuts and unscrew the wire from the green ground screw.
  4. Save the power cord—New disposals often do not come with a cord and plug. You can reuse your old unit’s power cord and reinstall it on the new unit if it’s a match. If not, you’ll need to purchase a new cord.
  5. Remove the existing mounting ring—You should remove the mounting ring only if it’s in bad shape. Keeping the current mounting hardware will make installing the new disposal quicker and easier. If the mounting ring needs to be replaced, peel away the rubber snap ring on the bottom of the mounting ring. The mounting ring should slide right off.

Installing a new garbage disposal

  1. Replace the sink drain—Use a pipe wrench to loosen and remove the nut securing the drain flange. Then, push the sink drain portion up through the sink for removal.
  2. Remove the old sink flange—The flange is a round, metal rim that encircles the drain opening. You should replace it only if it’s in bad shape. Push on the bottom of the flange from underneath then remove it from inside of the sink. Use a putty knife to remove any remnants of plumber’s putty where the flange sat.
  3. Install a new flange—Pat the drain opening dry with a paper towel. Place a ring of fresh plumber’s putty around the underside edge of the flange. Fit the flange into the drain and hold it in place for 30 seconds (or until the putty sets.) Replace the rubber gasket underneath the bottom of the new sink flange.
  4. Connect the new mounting assembly—Position the new mounting ring secure in place with screws. 
  5. Install the new disposal—Lift the new unit into position and twist the disposal to thread it into the grooves. Insert a screwdriver into one of the metal lugs and rotate the mounting ring clockwise until the disposal locks in place.
  6. Reattach the wires—Remove the faceplate on the new unit. Look for the matching colored wires on the power supply. Connect them using plastic wire nuts, and slip the copper grounding wire over the green screw at the far edge of the compartment. Replace the faceplate and tighten the screws.
  7. Reconnect the discharge tube and dishwasher hose—Align the tube with the valve on the side of the new disposal unit and push it in until it’s flush. If your unit is larger or smaller than the original, you will need to adjust the length of the discharge tube. If it’s too long, trim it with a hacksaw; if it’s too small, you’ll need to purchase a new tube. Reconnect the dishwasher hose.

Testing the new system

  1. Test for leaks—Turn on the water shut-off valves. Then, run water for a couple of minutes to see if there are any leaks.
  2. Test the garbage disposal—Flip on the circuit breaker. Once the unit has power, run the disposal. It should run smoothly and make no grinding or vibration noises.

If you don’t have the time, tools, or skills to replace your garbage disposal, consider hiring a professional plumber to complete the task for you.


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