When the water doesn’t drain in your sink, it can cause anxiety in any homeowner.
Is the plumbing busted?
Are you going to need to call the plumber?
The problem may seem even more strange if the sink only drains when the garbage disposal is on.
We’ll go over a few possible causes and how to fix them.
Sink Only Drains When Garbage Disposal is On (Causes, Fixes)
There are seven main reasons your sink will only drain if the garbage disposal is running.
Here’s what you need to know about them.
1. Seeds Are Clogging The Drain
If you have a habit of putting fruits and vegetables through the disposal, then you may have a problem with seeds.
Fruits, especially, have seeds that can clog your garbage disposal.
When the disposal’s clogged by the seeds, the water is unable to pass through the drain.
It’s only when the disposal is on, and the seeds slide through, that the sink’s water will drain.
Fix: De-Seed Beforehand
You should refrain from putting large pieces of food through the garbage disposal.
If you can’t avoid it, then you need to take the time to de-seed the food beforehand.
Cut out the seeds with a knife or spoon and throw them in the garbage.
When you pass the debris through the sink, the seeds won’t clog or jam the disposal.
As a result, the water won’t fill the sink.
It will pass through the drain.
2. Junk In The Disposal
Seeds aren’t the only thing that can block the disposal.
Junk often finds its way in there, too.
Items like wedding rings, keys, even wallets have fallen into the sink before.
Metallic objects are difficult for disposals to break down.
As a result, they remain inside the disposal and block the water from draining.
Fix: Remove Disposal And Empty Out Junk
You need to unplug the disposal and safely remove it from your sink.
Then open the disposal up and remove the junk inside.
You may be surprised at what you find lurking inside of it.
If you don’t want to open up the disposal, then you can use pliers.
Long pliers can reach deep within the disposal and grab onto the junk.
Then you just need to pull it through the top of the disposal’s drain.
You can also attempt to grab the junk through the flywheel with your fingers.
Removing the junk will open up the passage in the disposal.
When you attach it to the sink again, the water can pass through.
You’ll also protect the disposal’s blades by removing the junk.
3. Disposal Drain Is Too Low
The plumbing in your sink has two main drains.
There’s the drain that’s attached to the garbage disposal.
This drain is what water and debris pass through first.
The disposal rips up any debris in the process.
The water continues to pass through the pipes until it reaches a drain attached to the wall.
This drain empties the water and debris into the main water disposal line outside of your house.
Plumbing works with gravity to ease the stress on the pipes.
Everything slants downwards.
Your sink may not drain because the first drain, the disposal drain, is lower than the drain in the wall.
In this case, it forces the water to move upward instead of downward.
If the water doesn’t have enough pressure or force behind it, then it can cause the water to stall.
It ends up stuck and fills your sink instead.
Fix: Move Disposal Drain Higher
Fixing this problem is easy.
You need to unplug and detach the garbage disposal.
Then remove the drain that’s attached to the sink.
Purchase the same pipe but a shorter one to make the drain higher.
Then install the pipe to the sink and the garbage disposal.
When you use the water in the sink, it has an easier time running down the pipe towards the drain in the wall.
Water won’t pool in your sink.
4. The Garbage Disposal’s Flywheel Is Stuck
There are a few reasons your disposal’s flywheel may be stuck.
The first reason is seeds or debris.
If debris is large enough, then it can lodge itself between the gaps of the flywheel.
It will block the movement of the water and keep the flywheel from turning.
Another reason is build-up or sediment.
Older disposals may have a lot of gunk on their walls.
This is common in sinks that are used for the disposal of grease and fats.
It creates a sticky and thick layer of gunk on the walls of the disposal.
This can trap the flywheel and create a blockage that keeps water from passing through the drain.
The same goes for soap scum.
It can create a scaly residue that keeps the flywheel from turning.
As a result, the disposal blocks the water from draining.
Fix: Use An Allen Wrench To Turn Flywheel
In some cases, you may need to remove the debris that’s blocking the flywheel.
Unplug the garbage disposal and inspect the flywheel.
Look for anything that’s blocking its blades.
If there’s nothing there, then use the Allen wrench, or hex wrench, to turn the flywheel.
Moving it will force the wheel to unstick itself from any residue clinging to the disposal’s walls.
If you do see something, then remove it with your fingers or pliers first.
Then turn the flywheel with an Allen wrench.
Once it moves freely, you can plug the disposal back in and start it up.
The water will pass through the unblocked flywheel.
5. Plumbing Problem
To diagnose what’s going on with your sink, you need to test out other sinks.
Understanding what’s happening with your other sinks can tell you whether the problem rests with the specific sink or your plumbing.
Fix: Call A Plumber To Investigate
First, unplug and remove the garbage disposal from the problematic sink.
Then run the water through it.
If it does drain, then the disposal is the problem.
If it doesn’t drain, then the garbage disposal isn’t the problem.
You need to investigate more.
Test a different sink.
If it drains, then the problem rests solely with the other sink.
If it doesn’t drain, then put the garbage disposal on it.
Then test its draining ability.
If it drains, then the problem may be with your disposal.
If it doesn’t drain, then the problem is your plumbing.
Testing each sink can help you determine the location of the problem.
It may be that only the pipes connected to the particular sink are the problem.
If none of the sinks are draining, then it may be a larger pipe that they all feed into.
At this point, you’ll want to call your local plumber.
They’ll need to investigate the pipes leading outside to see if there’s a clog further down the line.
6. Inlet Pipe Is Broke
An inlet pipe, or vent, attaches the dishwasher and sink together.
It allows the water from each source to drain through the pipe in the wall.
Your sink may not drain because of a broken inlet pipe.
The reason it drains when the disposal is on is that the disposal applies pressure to the water.
The disposal provides enough force to make the water push through the broken pipe and go outside.
Fix: Repair Or Replace The Inlet Pipe
Repairing an inlet pipe is sometimes impossible.
The pipe may be wearing down, it may have become damaged, or it may just be missing.
You can find inlet pipes, or vents, at any hardware store.
Attach it to the correct spot in your plumbing system.
With the pipe in place, the water should pass through the disposal with ease.
It won’t require the disposal to be on to force the water through the pipe anymore.
7. Garbage Disposal Is Full
The final reason your sink only drains when the disposal is on could be that it’s full.
If you don’t run your disposal often, then it can fill with food and debris.
When the garbage disposal is full, water can’t pass through it.
The debris is blocking its access to the drain.
Fix: Empty The Garbage Disposal
Fixing this problem is simple.
You need to unplug the disposal and empty it.
The easiest way to do this is to remove the disposal from the sink.
Then gently tap the disposal against the trash can.
Hold the drain port above the trash.
The garbage will pass out of the drain hole and into the trash.
You’ll also need to use pliers to remove any food that’s stuck inside of it.
Once it’s empty, you can attach the disposal back to the sink.
Run cold water through it to flush it out.
The water should pass through without any problems.
How to Tell If Your Garbage Disposal Is Clogging Your Sink
Clogs can be difficult to diagnose.
You may not know if the clog is in the pipe or inside the garbage disposal.
Here are a few things to look out for that can help you determine if the disposal is clogging your sink.
1. Look For Whirlpooling In Sink’s Drain
A tell-tale sign that your sink has a clog is whirlpooling.
If you examine the water draining in the sink, then you may notice that it swirls as it goes down.
Sometimes the water will take some time to drain and form a whirlpool instead.
This is a sign that the sink is clogging.
The problem may come from your disposal.
You can fix the problem by running cool water through the disposal to wash it.
Run the disposal while you’re doing this.
Once the water drains normally, you know the clog is gone.
2. Other Sinks Function
You can also tell if the garbage disposal is causing a problem by examining the other sinks.
If the draining problem rests with your disposal alone, then the other sinks will drain.
Run water through your sinks, shower or tub, and even your toilet.
If everything drains as it should, then you know the garbage disposal is the problem.
You can further test it by attaching the disposal to a previously working sink.
If the sink no longer drains, then the problem definitely comes from the disposal.
3. Your Circuit Breaker Is Tripping
One final way to tell if the garbage disposal is clogging your sink is to look for tripped breakers.
The garbage disposal uses a lot of power to run.
If it becomes clogged, then it will keep using power to try and remove the clog.
The problem is that it can cause the disposal to overheat.
The wires may overheat, too.
It will send a short to the circuit breaker and cause it to trip.
Keep an eye on your circuit breaker when you run the disposal.
If it keeps tripping, then you know the disposal is overworking itself.
The reason is a clog.
How To Prevent The Garbage Disposal From Clogging Your Sink
If you have determined that the garbage disposal is clogging your sink, then you may want to know how to prevent that from happening again in the future.
Here are a few methods you can use to prevent the garbage disposal from clogging your sink.
1. Keep The Blades Sharp
Your garbage disposal can only work well if its blades are sharp.
Dull blades will have a difficult time cutting through debris.
The disposal will need to work harder to do the same amount of work with dull blades.
You can keep your blades sharp by running ice through the disposal now and then.
The ice chips help sharpen the blades by scouring the disposal.
The next time you run the disposal, the blades will have no problem chopping the debris to bits.
2. Wash Cold Water Through The Disposal Often
Any time you use the disposal, you should take the time to run cold water through it.
The cold water can help push any lingering debris through the blades and down the drain.
It also helps keep the disposal cool.
It’s easy for a garbage disposal to overheat and trip the circuit breaker.
It may overheat before it’s finished breaking up the food.
Running cold water cools the unit and allows it to finish the job.
This also prevents mold and mildew from growing as well as bacteria.
Warm water encourages bacteria and mold growth.
In the presence of organic food, mold and bacteria will thrive.
The cold water can discourage their growth and keep your disposal smelling fine.
Using warm water can also increase the disposal’s chances of overheating.
Run cold water through the disposal to remove debris and keep it from clogging your sink.
3. Prevent Overuse When You Can
You want to use the garbage disposal sparingly when you can.
Running it too long can overheat the motor and damage it.
The problem worsens when the disposal already has a clog.
If you suspect the disposal has a clog, then remove it first.
A long pair of pliers makes the job easier.
Test the flywheel while you’re maintaining the disposal to check its status.
Then let the motor cool.
After a few minutes, you can use the disposal again.
Give the garbage disposal breaks between uses to keep its motor functioning properly.
Without a functioning motor, food will fill the disposal up and clog your sink.
There are seven reasons your sink may only drain when the garbage disposal is on.
A problem with the garbage disposal, an incorrect height difference in the plumbing, and a clog further down the plumbing line are some of the possible causes.
The next time your sink doesn’t drain, consider the reasons above and follow the steps to fix it.
You can also use our tips to help prevent these problems in the future.