Why Is My Garbage Disposal Humming?

A humming garbage disposal often indicates a problem that needs attention. While it may seem like a minor issue, ignoring a humming disposal can lead to bigger problems down the road. In this comprehensive guide, we’ll explore the common reasons a garbage disposal hums and how to stop it.

What Causes a Humming Garbage Disposal?

There are several potential causes for a humming garbage disposal:

Something Stuck

One of the most common reasons a disposal hums is that there is something stuck in it. Food particles, broken glass, utensils, bones, fruit pits, and other debris can get lodged in the disposal blades and jam the motor. As the motor struggles to spin with an obstruction, it will make a loud humming noise.

To fix this issue, you’ll need to remove whatever is stuck in the disposal. First unplug the unit, then insert an Allen wrench or broom handle into the bottom of the disposal and turn it back and forth until it rotates freely. You can also use tongs or pliers to try and pull out visible items stuck in the disposal opening. Run cold water as you work to help wash away any loose debris.

Improper Assembly

If the garbage disposal was recently installed, it could be put together incorrectly. The grinding components inside the disposal may not be properly aligned, causing the motor to hum as it tries to spin.

You’ll need to realign the parts inside the disposal. Unplug the unit and look underneath to locate the wrenchette below the motor. Insert an Allen wrench into the wrenchette and rotate it back and forth to realign the internal components. Test to see if this fixed the issue by plugging it back in and running water. The humming should be gone if the disposal was reassembled properly.

Damaged Grinding Components

Over time, the grinding disks, flywheel, or shredder ring inside a disposal can become worn out or damaged. Dull shredder rings are a common culprit for humming disposals. The motor has to work harder to spin the damaged components, resulting in a loud humming noise.

Replacing worn internal parts may be required to stop the humming noise. You’ll need to unplug the disposal, remove it from under the sink, and disassemble it to inspect the grinding components. Replace any visibly damaged or worn parts. Reinstall the disposal, being sure all parts are aligned, and test for normal operation.

Bad Motor Bearings

Most garbage disposals use induction motors with ball bearings that allow internal components to spin freely. When these motor bearings start to wear out, it can cause friction that makes the motor hum loudly during operation.

Replacing defective bearings usually requires installing a brand new garbage disposal motor. This involves disconnecting all plumbing and electrical connections, removing the old disposal, swapping the motor, reconnecting everything properly, and making sure the new motor works without humming or issues.

Loose Wiring Connection

It’s also possible for vibrations from the disposal motor to loosen wiring connections. If power wires are not properly secured, it can interrupt the electrical current to the motor, making it struggle while humming loudly.

Check the wiring connecting to the garbage disposal for any loose wiring nuts or electrical connections. Make sure all wires are properly reconnected. Secure wires with electrical tape or zip ties to prevent vibrations from loosening the connections. Test to confirm the humming sound is gone after addressing any wiring issues.

Clogged Discharge Line

If the discharge pipe that drains water from the disposal is clogged, it can cause the motor to hum. Without a clear drainage line, the flywheel and grind ring will struggle to spin due to built up water pressure.

First unplug the disposal, then check inside the disposal drain port for blockages. Use a screwdriver or plumber’s snake to clear out any food, grease, soap scum, or debris clogging the drain line. You can also try flushing the line with boiling water. Once drainage is restored, the humming should stop when the disposal is used.

Bad Flywheel

The flywheel is a critical grinding component that allows the disposal blades to rotate freely. Over time, this flywheel can warp or jam, causing friction that makes the motor hum. Often a bad flywheel is accompanied by a burning smell from the disposal.

Replacing a damaged flywheel usually requires installing a new garbage disposal unit. Make sure power is disconnected before removing your existing disposal. Then install the new unit with a properly functioning flywheel, reconnect drains and wiring, and test for normal quiet operation.

How to Diagnose the Exact Cause of a Humming Disposal

It can sometimes be challenging to pinpoint exactly why your garbage disposal is humming. Here are some tips to help diagnose the issue:

  • Listen carefully – Note where the humming is coming from and whether the sound changes when you turn on the faucet. This can help determine if it’s a motor issue or a drainage problem.
  • Look inside – Unplug the disposal and shine a flashlight down into it. Look for obstructions, damaged parts, or clogs. Spin the flywheel by hand to check for stiffness.
  • Feel the motor – With it unplugged, touch the motor when the unit hums to feel for vibrations. Too much vibration can mean worn bearings. Steady humming may indicate jammed internal components.
  • Check wiring – Inspect connections to the disposal for loose, damaged, or corroded wires that could cause humming.
  • Assess the age – If your unit is more than 10 years old, the motor may simply be worn out, requiring a new disposal. Newer models should last 15+ years.
  • Consult an electrician – For perplexing electrical issues like humming even when turned off, contact a qualified electrician to inspect the wiring and diagnose the problem.

Being methodical and working through these troubleshooting steps can help zero in on why your disposal is making a bothersome humming sound.

How to Fix a Humming Garbage Disposal

Once you’ve diagnosed the cause of the humming, follow these tips to stop the noise:

Clear Jams

If there is something stuck in the disposal, unplug it and carefully remove the obstruction. Use tongs, pliers, an Allen wrench, or a disposal jam tool. Don’t reach inside with your hands. Running cold water can help clear debris while you work. Test your disposal after removing any jams. The humming should be gone.

Tighten Mounting Bolts

A disposal that is loose under the sink can vibrate and hum. Use a wrench to tighten the mounting ring bolts until snug. Don’t overtighten, as this can crack the sink flange. Test the disposal to see if tightening the mounting dampened the humming.

Lubricate Internal Parts

If the grinding components are dry, lubricating them with food-grade machine oil can help eliminate humming. Unplug the disposal, then coat the flywheel, grinding ring, and shredder ring with oil. Spin the flywheel to distribute the lubricant. Plug back in and run the disposal to test if the oil fixed the issue.

Replace Worn Parts

Worn or damaged internal components often need replacement to stop humming. Match the make and model when ordering replacement parts. Common parts to replace include the flywheel, shredder ring, and grinding disk. Installing new parts according to manufacturer instructions should resolve any humming.

Install New Disposal

For older disposals with defective motors or extensive internal damage, replacement is the best option. Choose a same-size unit and install it following all manufacturer instructions for your sink type. Make sure to also replace any corroded drain pipes or faulty wiring. A new garbage disposal should operate smoothly and quietly.

Tips to Prevent Future Humming Issues

Follow these tips to keep your garbage disposal running smoothly for years to come:

  • Run cold water – Always run cold water through the disposal when grinding to wash debris down the drain. Cold water keeps the motor cool and prevents warping.
  • Flush regularly – Flush the disposal with hot water and baking soda once a month to clean the drain line and deodorize.
  • Grind carefully – Avoid very hard or fibrous foods like bones, celery, onion skins, eggshells, and pits that can jam the disposal. Grind rinds and peels carefully.
  • Check for jams – If the disposal makes a different noise, unplug and check for obstructions. Clear jams right away to prevent damage.
  • Inspect internally – Periodically remove the flywheel or inner cover to check for worn parts. Replace components early before they fail completely.
  • Lubricate as needed – Use food-grade machine oil every few months to maintain lubrication inside the disposal grinding chamber.

A little prevention goes a long way towards maintaining a problem-free garbage disposal. Following these tips will help stop annoying humming and maximize your disposal’s lifespan. Act quickly when noises do occur – catching problems early is key to smooth and quiet operation.

Frequently Asked Questions About Humming Disposals

Why does my garbage disposal hum even when turned off?

A disposal that is humming even when powered off usually indicates an electrical issue. There may be a faulty wire connection that is causing the motor to vibrate. Check all the wiring connections to the unit and make sure hot and neutral wires are not reversed. Consult an electrician if you cannot find the wiring problem.

Why is my new garbage disposal humming?

If a brand new disposal is humming, it likely wasn’t assembled correctly. The internal components are probably misaligned, causing friction as the motor spins. You’ll need to realign the parts according to the manufacturer’s directions to stop the humming.

Can I lubricate my garbage disposal to stop humming?

Yes, lubricating the internal components can help reduce friction that causes humming. Use a food-grade machine oil and coat the flywheel, grind ring, shredder ring, and other rubbing parts. Run the disposal with water afterward to distribute the lubricant evenly. This can stop minor humming.

What happens if I keep using a humming garbage disposal?

It’s important not to ignore a humming disposal. The friction that causes the noise can eventually lead to the motor burning out or internal components failing. A jammed disposal can overheat, smoke, leak, or damage sink plumbing. Have humming issues addressed promptly.

How do I know if my garbage disposal needs to be replaced?

Signs your disposal needs replacement include humming even after repairs, advanced age (over 10-15 years old), leaking from a cracked housing, corroded or damaged electrical connections, or extensive internal wear or damage. Replacement is generally the only fix for major issues like these.

Key Takeaways: Solving Garbage Disposal Humming

  • Persistent humming from your garbage disposal indicates a problem needing attention.
  • Common causes include something stuck, improper installation, damaged internal parts, bad motor bearings, loose wiring, or inadequate drainage.
  • Diagnose the cause by thoroughly inspecting the unit and connections, feeling the vibration, and checking component wear.
  • Clearing jams, tightening mounts, lubricating, replacing worn parts, and installing new disposals can all stop humming.
  • Be proactive with regular maintenance and quick repairs to maximize your disposal’s life span.
  • Addressing any humming issues promptly prevents more extensive damage long term.


A humming garbage disposal can be bothersome, but identifying the cause is the first step toward solving the problem. While humming can indicate serious issues like worn motor bearings or jammed blades, many causes like obstructions and loose mounts are easy fixes. With routine maintenance and timely repairs, your disposal can continue grinding quietly and reliably for years. Diagnose any unfamiliar humming sounds right away, and take action to restore your disposal to smooth and quiet operation.