Why Is My Garbage Disposal Leaking From the Bottom?

Garbage disposals are the ultimate kitchen workhorses, and while a well-maintained unit typically lasts five to ten years, all that grinding can lead to malfunctions. Leaks need prompt attention as they can cause under-sink odors, dampness, damage, and, in worst-case scenarios, electrical risks. It’s possible to repair some sources of seeping yourself but when your garbage disposal is leaking from the bottom, a quick patch-up isn’t always possible.

I spoke with a licensed plumber and garbage disposal manufacturer to understand what causes garbage disposals to leak from the bottom and why replacement is often the best solution.

What Causes a Garbage Disposal to Leak From the Bottom?

Licensed plumber Shaylin King says a close examination is necessary to establish the cause of a garbage disposal leaking from the bottom.

Worn internal seals

King explains that even the best garbage disposals have a limited lifespan. “The most common cause of garbage disposals leaking from the bottom is failure of the seals around the internal bearings due to old age,” he says.

Worn gaskets

According to King, gasket deterioration commonly occurs in two spots, causing dripping from the bottom of the unit. “The first potential leak location is the gasket where the disposal meets the flange [a ring connecting the disposal to the sink],” he says. While the leak is actually at the top of the unit, it drips down and could look like the water is escaping from the base. “The second potential leak location is the gasket where the drainpipe leaves the disposal.”

Cracked shell or corrosion

While less common, age-related cracks can form in the interior shell of the unit, leading to dripping from the base. Jeremy Gattozzi, Senior Category Manager of Disposals at Moen, says this is also true of corrosion.

Loose connections

Improper installation and time loosen screws, compromising the seal on your garbage disposal unit.

How to Identify the Source of a Garbage Disposal Leak

Identifying the source of the leak is your first step towards deciding if fixing a garbage disposal leaking from the bottom is possible. Gattozzi recommends disconnecting the unit and inspecting it for any clogs, cracks, corrosion or other visible damage. If you don’t see anything obvious, he suggests conducting a leak test using the following steps:

1. Fill the sink with water.
2. Wrap paper towels around the sink flange at the top of the unit to help identify if there’s an issue with the upper gasket.
3. Wrap paper towels around the drain discharge (the elbow connecting the disposal base to the pipework) to identify any issues with the lower gasket.
4. Release the water from the sink and check if the paper towels are wet.

If you can’t identify the source of the leak from your disposal, it could be coming from elsewhere. You might need to fix a leaky faucet, countertop seams or dishwasher.

Can You Fix a Garbage Disposal Leaking From the Bottom?

Whether you can fix a garbage disposal leaking from the bottom depends on the cause of the drips and the condition of the unit.

• Loose connections: A DIY or inexpensive pro fix is typically possible.
• Corrosions or cracks: You’ll need to invest in a new disposal.
• Faulty gaskets: It’s possible to fit new gaskets. “However, by the time they start leaking, the disposal has generally exceeded its lifespan, and replacement should be considered,” King says.
• Other seal failures: Some units have internal seals that aren’t designed to be replaced, or if one goes, others are likely to follow. In these instances, replacement is the best or only option.

How to Fix a Garbage Disposal Leaking From the Bottom

If you’re confident with your DIY skills and trace the leak to faulty gaskets, it’s possible to replace them. The guidelines below are high-level always check the disposal manual for model-specific instructions.

1. Clear out the space under your sink for convenient access.
2. Unplug and disconnect the garbage disposal wiring and water supply.
3. Use a wrench to remove the disposal.
4. Remove the rubber gasket at the top or base of the unit.
5. Replace with a new gasket.
6. For the flange gasket, add a new seal of plumber’s putty.
7. Reconnect the disposal and tighten the mounting rings.
8. Reconnect the water supply and power.

When to Call a Pro

While it’s possible to do basic repairs yourself, such as tightening loose screws or replacing gaskets, mistakes can be costly. Gattozzi recommends calling a professional if there’s extensive damage, you’re struggling to identify or stop the leaking, or you don’t feel comfortable attempting repairs.

King explains that a garbage disposal leaking from the bottom often signifies that the unit is nearing the end of its life. Sometimes, it can fail due to internal seal breakages and won’t be repairable. In these instances, replacement may be the only option. King also recommends calling a professional if you aren’t entirely confident in your ability to replace your garbage disposal unit.

FAQs

Why is my new garbage disposal leaking from the bottom?

“A bottom leak from a new garbage disposal is most likely due to an issue with the unit’s installation,” Gattozzi says. King says there’s a good chance the leak is coming from one of the two gaskets. Unlike leaks from older units, simple repairs under warranty typically resolve the issue.

Is a garbage disposal leak a sign I need to replace it?

The type of garbage disposal leak affects whether the unit needs replacing. Worn-out internal seals are the most common cause of leaks from the base of an older model. “If this is the case, then buying a new unit is your best move unless you’re still under your provider’s warranty,” Gattozzi says.

About the Experts

Jeremy Gattozzi is the Senior Category Manager of Disposals at Moen. The company is one of the world’s largest manufacturers of plumbing products, including garbage disposals; email interview, May. 13, 2024

Shaylin King owns Mr. Rooter of Tri-Cities, Yakima, and Hermiston, a Neighborly company. He is a 25-year journeyman plumber; email interview, May. 8, 2024.