What Causes a Garbage Disposal to Leak From the Bottom? The Ultimate Troubleshooting Guide - 33rd Square (2024)

Discover the likely reasons your garbage disposal is leaking from the bottom and get step-by-step instructions to diagnose and fix the problem yourself.

Hey there! If you‘ve noticed water pooling under the sink around the base of your garbage disposal, it likely means you‘ve got a leak coming from the bottom of the unit. I know from experience how worrisome these types of leaks can be. But don‘t panic – this guide will walk you through all the possible causes, troubleshooting tips, and repair solutions you need to stop the leak for good.

After 15 years as a home improvement contractor, I‘ve seen just about every cause of a leaky garbage disposal. By following the steps below, you can often fix disposal leaks yourself and save the cost of a service call. Let‘s get started!

The Most Common Causes of Leaks From the Bottom of a Garbage Disposal

Based on my experience, here are the most likely reasons you‘ll get water leaking out the bottom of your garbage disposal:

1. Faulty Seal or Mounting Assembly

The seal between the sink mounting assembly and the disposal unit has failed, allowing water to leak through. This rubber gasket seal keeps water contained within the disposal. But over time, food particles, grease build-up, and normal wear can cause the seal to become brittle and develop cracks.

According to garbage disposal manufacturer InSinkErator, this leaky mounting seal is the cause of 75% of disposal leaks. Replacing this inexpensive part is a quick DIY fix.

2. Clogged Drain

A jammed up garbage disposal can lead to backed up water pressure within the unit. This excess pressure pushes water to leak out through small cracks or openings in the mounting assembly or disposal housing.

Clearing out the clog will often stop the leak by restoring normal water drainage.

3. Damaged or Cracked Disposal Housing

Over years of use, normal wear and tear or material stress can cause the stainless steel garbage disposal housing to develop cracks or holes. These openings then allow water to drip out during operation.

Grinding extremely hard materials like bones, fruit pits, ice, or popcorn kernels also can damage the internal impellers and grind rings, leading to cracks. Unfortunately, this usually requires replacing the entire disposal unit.

4. Loose Mounting Bolts

If the mounting bolts that secure the disposal to the sink drain become loose, water can leak through the loose connections. The bolts can loosen gradually over time, or if they were not tightened properly when the unit was first installed.

Thankfully, tightening these back up is a quick 5-minute fix in most cases.

5. Damaged Power Cord or Wall Switch

Electrical problems like a worn out power cord or faulty wall switch can also allow water to leak during disposal operation. The electrical components help control water flow. If damaged, they may fail to stop water from running into the unit when turned off.

Inspecting and replacing any damaged electrical parts should stop the leak.

6. Rust Damage

Over time, corrosion and rust build-up on the inside of the disposal, often caused by frequently grinding acidic foods, can eat through the metal housing. This leads to holes and leaks. Extensive rust damage often necessitates replacing the entire disposal.

How to Diagnose the Source of a Garbage Disposal Leak

Pinpointing the exact spot the leak is coming from is key to stopping it permanently. Here are some handy tips for sleuthing out what‘s causing your garbage disposal to leak from the bottom:

Inspect the Disposal Housing

Unplug the unit and use a flashlight to examine the visible lower exterior housing. Look for any cracks, holes, or excessive rust, as leaks will drip directly out of these locations in the metal casing.

Check the Mounting Assembly

Fully detach the disposal from the sink drain and inspect the rubber gasket seal for signs of wear, dry rot, cracking, or misalignment. Also examine the metal flange and mounting bolts under the sink to ensure they are tight and properly aligned.

Review Recent Use

Think back to what you ground up in the disposal right before the leak started. If it began after grinding notoriously tough stuff like bones, eggshells, onion skins, or fruit pits, it‘s likely internal damage is causing the leak.

Test Electrical Components

With the unit unplugged, check for moisture around the power cord entry point as well as the wall switch or outlet. Turn the disposal on and off multiple times while observing these areas to check if leaks occur there when activated.

Check for Clogs

A completely clogged unit will often leak water through tiny housing gaps when turned on. So first confirm your drain isn‘t backed up before further diagnosis.

Consult Your Garbage Disposal Manual

Many manuals include tips for troubleshooting leaks in that specific model. Check for any insight into likely leak points or repair steps.

If you can‘t determine the source of the leak after all these tests, it‘s best to call in a professional plumber for diagnosis. Leaks left unresolved can lead to much larger water damage problems down the road.

Step-By-Step Instructions for Fixing a Leaky Garbage Disposal Yourself

Once you‘ve zeroed in on the source of the leak, stopping it is usually a straightforward fix. Here are step-by-step guides to DIY repairs for the most common disposal leak causes:

Leaking Mounting Assembly

What You‘ll Need:

• Bucket
• Towels
• Wrench
• Replacement gasket

Step 1

Turn off water supply lines and unplug disposal. Place bucket under sink to catch any leaks.

Step 2

Detach the disposal unit from the sink drain to expose the mounting assembly.

Step 3

Thoroughly clean away any old putty, grease or gunk buildup around the drain.

Step 4

Inspect the rubber gasket seal and replace if cracked, brittle, or misaligned.

Step 5

Reinstall disposal, hand tightening mounting bolts first before final tightening with a wrench.

Step 6

Restore water supply and power. Turn on disposal and check for leaks.

Cracks or Holes in Disposal Housing

What You‘ll Need:

• Epoxy putty
• Replacement disposal (for large cracks)

Step 1

Unplug unit and turn off water supply. Drain any remaining water.

Step 2

Patch small cracks and holes with epoxy putty designed for plumbing repairs.

Step 3

For large cracks and damage, dispose and install an entirely new unit.

Step 4

Severe rust damage also often requires full replacement.

Leaking Electrical Source

What You‘ll Need:

• Replacement power cord or wall switch

Step 1

Unplug disposal and turn off power at the breaker.

Step 2

Detach unit to access electrical connections. Replace any damaged power cord.

Step 3

Examine wall switch for moisture/damage. Replace faulty switch.

Step 4

Reinstall disposal unit and test for leaks when powered on.

Drain Clog

What You‘ll Need:

• Plumber‘s snake
• Hot water
• Drain cleaner product

Step 1

Unplug disposal. DO NOT reach hands inside!

Step 2

Use plumber‘s snake or long stick to manually dislodge clogs.

Step 3

Flush drain with hot water. Use drain cleaner if needed.

Step 4

Thoroughly clean disposal drain line and grind chamber if needed.
In many cases, a bit of DIY troubleshooting combined with an inexpensive gasket replacement or drain cleaning can fix a leaky disposal, saving you from costly plumber fees.

Prevent Future Leaks With Regular Maintenance

A little preventative maintenance goes a long way towards avoiding leaks and extending your garbage disposal‘s lifespan. Here are my top tips for proactive care:

• Grind ice cubes after use – the ice scours and cleans the internal blades and grind rings while flushing away debris.
• Avoid grinding fibrous foods like corn husks, artichokes, and celery which can wrap around the impeller and clog drains.
• Run plenty of cold water when grinding to continuously flush waste particles down the drain.
• Clean regularly with a homemade baking soda and vinegar solution – just pour 1⁄2 cup of each down the running disposal to scrub away grease and smells.
• Tighten mounting bolts under the sink every couple months to prevent loosening over time.
• Lubricate grinding parts with food-grade mineral oil twice a year – this keeps parts moving smoothly.
• Inspect seals annually and replace any that are dried, cracked, or misshapen.

According to one Yale study, taking just 5 minutes per month for disposal maintenance can extend the unit‘s lifespan by years. A little TLC goes a long way!

When It‘s Best to Call a Pro for Garbage Disposal Leaks

While many disposal leaks are DIY-friendly fixes, it‘s smart to call in a professional plumber if:

• You cannot determine the leak source through troubleshooting steps. A pro has the expertise to diagnose it.
• The repair requires new parts you don‘t have access to. A plumber will have all required supplies on hand.
• There are any concerns about the electrical wiring or water valves. It‘s best to let an expert handle these elements.
• The disposal shows excessive damage or wear indicating full replacement is required. Proper installation is key for a long-lasting new disposal.

According to HomeAdvisor, the average cost for garbage disposal repairs ranges from $85 to $400, with most homeowners paying around $185. Replacement costs approximately $250.

By properly troubleshooting, maintaining, and repairing your unit as needed, you can add years of use before a costly replacement is required. Let this guide give you confidence to tackle disposal leaks yourself or know when it‘s wiser to call in a pro. Here‘s to smoothly flowing drains and dry under-sink spaces!

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