Sink Only Drains When Garbage Disposal Is On? (Fix It Now!)

Ossiana Tepfenhart
by Ossiana Tepfenhart

As a kitchen fan, there are few things as terrifying to me as seeing a kitchen sink that’s clogged. It’s an issue that can wreck a day of cooking and also cause severe damage to your favorite room. Sometimes, though, clogs aren’t just clogs. For example, sometimes, the sink might only drain when the garbage disposal is on. What gives? And more importantly, how do you fix it?

If your sink only drains when the garbage disposal is on, then that means you have a clog that’s affecting your garbage disposal. This is usually an easy fix that requires you to turn off the garbage disposal and use a plunger to remove the clog. If no clog can be found, this can mean that your garbage disposal is broken.

Dealing with a slowly-draining sink, or worse, a sink that won’t drain at all, is annoying, but it is no reason to panic. This guide will show you how to diagnose and handle your garbage disposal woes and how to prevent it from happening in the future, hopefully.

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Why Won’t My Sink Drain Without The Garbage Disposal Being Turned On?

This is the big question at hand, and the truth is that there are only a couple of common causes of this issue. These issues typically include:

  • A Broken Garbage Disposal. Sometimes, the garbage disposal that you have is just acting wonky. In most cases, you might be able to fix it by just restarting it or replacing it.
  • A Clog. Most of the time, this is a real problem.
  • A Jammed Disposal. If the garbage disposal is genuinely jammed, then removing the clog won’t be able to be done using traditional plumbing methods.
  • A Fully Disposal. If you’ve shoved a ton of food into your garbage disposal, this will need to be chopped up before the sink wants to drain.

How To Troubleshoot Your Draining Problem

Trying to get your drain to work appropriately is all based on figuring out what’s going on with your drainage system. So, you’re going to need to troubleshoot it. Here’s how to get a diagnostic going and hopefully fix things in the process…

Is My Garbage Disposal Glitching Out?

Sometimes, the garbage disposal you have is the problem–but it won’t be a jam. Some models tend to stop up, which can cause a blockage that’s only ended by turning the disposal on. This is a pretty easy fix. Just try to turn the garbage on and off a couple of times, then try to run the water.

If it’s still going, turn the garbage disposal off, then use an Allen wrench to turn the grinder’s shaft from the bottom exterior of your garbage disposal. If it can turn smoothly in a complete circle, and you don’t hear any strange clunking or grinding noises, you should not worry about the disposal being the problem.

What If My Garbage Disposal Is Busted?

If the issue is your garbage disposal, you are going to need to replace it. However, if it’s not entirely broken, you will need to check it. If something is going on with the housing, or the motor, you might be able to fix these problems pretty easily rather than purchasing another $300 disposal. It all depends on your situation and the issue.

How To Get Rid Of Sink Clogs

Now that we know that the garbage disposal isn’t busted, you are going to need to get rid of the clog (or disposal jam) that’s causing the slow drainage. Here’s how you can get rid of clogs and have your sink flowing back to normal:

  • Unplug your garbage disposal. This is just a safety measure. It would be best if you never plunged while it’s on.
  • Use a toilet plunger, and cover the drain’s hole completely. Plunge like you would a toilet. This should be enough force to get rid of the clog.
  • Use water to rinse out the clog. The clog should disappear. Once it’s good to go, plug the disposal back in again.
  • Pour some cleaner into the disposal. There are some garbage disposal cleaners out there that help to eat away any clogs within your disposal. Follow the instructions to clear your drain.

What Should I Do If The Clog Doesn’t Get Loose?

Honestly, this is an excellent point to hit the pause button and call a professional. A clogged sink that has a deep-set clog may require to be snaked. The problem is that snaking the plumbing can cause severe damage to pipes, primarily if it’s corrupted. We do not suggest doing this on older piping and would go so far as to say it’s something to leave to the pros.

If you do decide to use a snake, remove the garbage disposal first and then snake the branch that leads to your main plumbing system directly. This can and should remove any clogs that aren’t superficial.

How To Fix A Jammed Garbage Disposal

Let’s say that you don’t think a clog is the culprit for your non-draining sink. In fact, you actually were able to get it confirmed that you weren’t dealing with a clog. In this case, the only other thing you can do is try to unjam the garbage disposal. Here’s how:

  • Unplug the garbage disposal and place a bucket underneath the disposal’s drain trap. This is where all the sludge goes when you use a garbage disposal.
  • With channel-type pliers, loosen the slip-nut fillings on your drain trap. Remove the drain trap and let the water and waste pour into the bucket. If you notice something stuck, reach in and carefully scoop it out.
  • Clean the trap using a scrub brush. Pipe cleaners can also work.
  • Next, check the trap’s arm. This is the second-most commonplace location of a clog or a jam. Scoop out any excess waste you see here. You can remove the trap arm by loosening the slip nut. To remove any extra clogs, use the scrub brush to clean out the arm.
  • Reassemble your garbage disposal. Now that your disposal is all clean, you should be able to see your sink drain away with ease.  Plug your disposal in.
  • Flush it out with water. If you’re concerned about residue, add some enzyme-based drain cleaner to the drain after you rinse it out with water.

When Should You Call A Plumber?

If you are still unable to get your sink to drain without turning on the garbage disposal, you have a mystery on your hands. A good rule of thumb is to call a professional whenever you don’t have the tools, the knowledge, or the experience to fix things yourself. After all, it’s always better to be safe than sorry.

Also, if there are any backups with your tub, or your toilets or sinks, then the issue may not be your garbage disposal. There could be a clog somewhere in the main plumbing unit. Or, if you’re on a septic tank, they are a sign that your septic is full, and you will need to pay someone to empty it.

Related Questions

What causes a garbage disposal not to drain?

One of the most common causes of a clogged drain is the clogging of your garbage disposal. When you fix the clog in your garbage disposal, then your drain should work with no problems. If not, then the problem is within your drain.

When I turn on the garbage disposal, the sink backs up?

If your sink is backing up when you’re using your garbage disposal, you will need to use a plunger. There may be something that’s stuck that you need to help dislodge further down in the piping.

How much does Home Depot charge to replace a garbage disposal?

To replace a garbage disposal, Home Depot will charge about $119 for installation. This price is not inclusive of the disposal itself. So you will need to purchase the device itself, which will run between $80 to $500. Then, add the $119 installation fee to this price, and you have your total price before tax.

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Our Final Take

Garbage disposals can be a fantastic addition to your kitchen, but only if they’re working correctly. If you find yourself in a situation where your sink only drains when the disposal’s turned on, you might be a little discouraged. But don’t be. In the vast majority of cases, this problem is a relatively easy fix that can be performed using standard household tools.

The key to making your sink flow again is to troubleshoot everything in order and to fix any issues that you notice while you’re working through the troubleshooting procedure. If things go smoothly, the fix you need should take under an hour’s time. Of course, there may be moments where you don’t have the right tools or where most common issues aren’t what’s causing your drain to get stuck.

If you’ve worked through the guide without much success, the next best thing you can do is call a handyman or a plumber to help you out. Asking for help is always ends up being a smart move, after all.

Ossiana Tepfenhart
Ossiana Tepfenhart

Ossiana Tepfenhart is an expert writer, focusing on interior design and general home tips. Writing is her life, and it's what she does best. Her interests include art and real estate investments.

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