Why is the Garbage Disposal Leaking?

When you see water dripping off the bottom of the garbage disposer you may think that it has to be replaced.  But that’s not necessarily true.

Sometimes the leak can be repaired.  The first step to making the repair/replace decision is to determine from where the leak is coming. 

 

Garbage disposer leaks usually come from one of five places:

1.The sink flange – where the sink and the disposal unit directly connect – see image below:

sink flange

2. The dishwasher hose connection – where the hose and the disposal connect – see image below:

dishwasher hose connection

 

3. The drain – where the drainage discharge pipe and the disposal connect – see image below:

the drain

 

4. The seals – water actually leaking from the very bottom of the disposal – see image below: 

seals

 

5. The motor housing – from a crack in the body of the disposal – see image below:

motor housing

 

Before you decide about repair or replacement, determine the age of the disposal.  If it is a really old disposal unit, you may want to consider replacing it regardless of the source of the leak.  

When a disposal is replaced, the source of any leak on the old one will be repaired anyway, and tossing good money at an antique disposer that may present you with a second leak (or a motor or impeller failure) a short time later is probably not a good idea.

If you determine the disposer is worth salvaging, then the source of the leak has to be determined in order to find out if it can be repaired.  

Where is the garbage disposal leaking?

The first thing you have to do is find out where the leak is coming from.  If the leak is obvious (i.e. pouring out the side from a gaping hole or squirting out between the sink and the top of the disposer) then just find your section below and follow the instructions. 

Otherwise, finding the source requires you to use a very specific technique. Remember, gravity makes water run downward so a drip at the bottom may be coming from the top. 

To start, take your absolutely dry finger and run it all the way around the highest point (up against the bottom of the sink where the disposer meets the sink).  Check your finger in a lighted area to see if there is any water on it. If so you have found your leak.  

If there is no water there, work slowly down the disposer, running your finger around the entire circumference and checking for water each time. 

When your finger comes back wet, you have found the leak. Take your flashlight and see if you can see the part that is leaking. If so, you can find the pertinent section below for instructions and suggestions. 


Let’s go through all 5 leak sources in your garbage disposal and see what needs to be done to facilitate a repair (or if the repair is even possible).  

ALWAYS DISCONNECT ELECTRIC SOURCE FIRST.

1. The sink flange

HOW TO FIND OUT IF THE FLANGE IS LEAKING:

This type of leak is always located at the top of the disposer when looking at it from under the sink.  Don’t be fooled by water dripping from the bottom of the disposer. Remember, gravity makes water run down so a drip at the bottom may be coming from the top. 

The way to tell is to take your absolutely dry finger and run it all the way around the highest point (up against the bottom of the sink where the disposer meets the sink).  Check your finger in a lighted area to see if there is any water on it.

If so, you have found your leak. If not, it is not a leaking sink flange.  Remember—when you track down the source of the leak to the very top of the disposer it is most likely a leak from the sink flange

THE FIX

If the sink flange is leaking, it can be removed (see instructions below) and the leak repaired.  Most disposers have a dual sealing system for the sink flange.  

First, there is a ring of plumber’s putty installed between the sink flange and the sink surface – see image below:

sink flange leaking

If this putty gets old and hard, it can crack due to the vibration of the disposer.  If this is the case, you will need to remove the top (finished—chrome, brushed nickel, etc.) flange and scrape off the old putty from the sink and the flange.  Then replace the putty with new. See below for this process.

Second, there is usually a rubber gasket attached to the disposer which seals against the bottom of the sink when the disposer attachment flange is tightened.  

Sometimes the disposer vibration will cause the mounting mechanism to loosen up.  Simply tightening the mounting mechanism will solve the problem in this case about 99% of the time.

Putty is easily obtained at the hardware store and the gasket, if standard, is available there also – see images below:

plumbers putty

gasket

If yours is a nonstandard gasket, one will have to be obtained from the manufacturer or his representative in the area.

If you want to do this yourself, first disconnect the waste line from the disposer by removing the two bolts that clamp the waste line and gasket into the disposer waste opening – see image below:

disconnect waste line

Then, remove any other drain assembly nuts and pipes under the sink necessary to pull the waste pipe out of the disposer waste opening.

Next, determine how your disposer is mounted. There are basically two types of standard mounting mechanisms for disposers.  The disposer unit is either clamped onto the flange with a rotating mechanism or is clamped in place with a worm gear type clamp.  

Use a long sturdy Phillips screwdriver to loosen the clamp if it is the first type – see image below:

clamp

Rotate the clamp counter-clockwise to loosen until the disposer unit is disassembled from the flange. It will be reassembled in the same way.  

If the disposer is held on with a worm gear clamp, simply loosen the nut on the clamp (counter-clockwise) until the disposer can be pulled down from the flange.

Keep in mind that when you remove the clamping mechanism the disposer will fall down.  Be ready for that!

The disposer flange will usually be removed by loosening a series of (usually 3 vertical) attachment slotted bolts/screws – see image below:

garbage disposal flange

Turn the bolts counter clockwise until the ring in which they are held is loose and can be pushed up about a ¼ inch or more.  Then using a flat tipped screwdriver, remove the snap ring (if necessary) to allow the clamping unit to fall into your hand. See picture # 12.

snap ring

Note, if there is no snap ring, then rotate the clamping ring either way until it falls down into your hand.  Now you can push the top flange up through the top of the sink opening.

Scrape off all the old putty from the flange and sink opening and reverse this procedure after installing a new thin ring of plumber’s putty to the underside of the flange so that the putty is between the sink and flange – see image below:

sink flange leaking

Don’t use a lot of excess putty!  This will cause more problems.

Reassemble your components in the reverse order from that explained during disassembly above. Test your disposal assembly for leaks and you are all set.

It’s prudent to note that this repair takes at least as much time as installing a new disposer.  Consider that fact and the age of your disposer when you decide to repair or replace.

Beware that if the garbage disposer is leaking here, corrosion may require extra effort or professional tools and skills to remove the flange.

2. Dishwasher hose connection

In some states, it is not legal to connect the dishwasher drain hose to the garbage disposer because of the risk of contamination of clean dishes and utensils.  

If your state allows this, then the hose may be connected to a barbed fitting that is molded into the grinder housing.

sink flange leaking

If it is leaking due to a loose or missing clamp which should be installed over the end of the dishwasher discharge hose, then tightening or installing a new clamp will do the trick.  

Be sure that the end of the hose is not cracked when you take it off the end of the barbed fitting.  If the barbed fitting on the disposer itself is cracked, then the disposer unit will need to be replaced.

3. Drain connection

If the source of the water is the drain connection, this too, can almost always be repaired.  

The drain will either be connected with a flanged elbow or a flanged straight tailpiece.  In either case the leak can be caused by a cracked flange on either piece, a bad gasket, a loose clamp or a cracked housing.  If the tailpiece is bad it must be replaced.  

We always change the gasket when this is the case since it is inexpensive and removal of the old tailpiece can damage it.  

If it’s the gasket, those can be obtained at the local hardware store.  They are all the same.  

The tailpiece and gasket are held in place by a circular piece of steel with a protrusion on one end.  The protrusion fits into a slot in the disposer body and a screw fastens the other side into the disposer body compressing the gasket while acting as a retainer over the flange.  

Of course, if the clamp is just loose, tightening the bolt should stop the leak.  Be sure to check for the cause of the loose bolt so that it doesn’t happen again.  If the housing for the clamp is cracked and leaking, the disposer must be replaced.

4. Disposer seals

A leak from the very bottom of the disposer indicates a bad seal or a cracked housing.  If the disposer shaft seals are determined to be the source of the leak then the disposer must be replaced.  

Follow the procedure under “The Sink Flange” above to remove the old disposer.  

All disposers we know of are sealed units and cannot be field repaired. 

5. Motor Housing

A cracked motor housing is a very rare occurrence but unfortunately, when this does occur, the entire disposal must be replaced.  

This is also a dangerous situation as water and electricity definitely don’t mix.

Easiest fix of all

Call Yes! Plumbing anytime for help if your garbage disposal is leaking. Operators are standing by to serve you 24/7.

If you think your garbage disposal is not leaking but you think it’s broken, read our guide on simple fixes for a broken garbage disposal.