Sink Only Drains When Garbage Disposal is On (What to do?)

Plumber Repairing a Kitchen Sink

Flickr Commons image via TWP Inc.

If you have ever experienced a clogged sink you know how annoying and disgusting it can be. Whether your kitchen sink is draining slowly or doesn’t seem to drain at all, there may be a simple fix. If you have a garbage disposal on the other side of the sink you may have noticed that your clogged sink will drain when you turn on the disposal but not on its own.

We will review a few easy steps for you to try to get that sink back to draining on its own instead of needing to run the disposal in order to drain your sink.

If you think you might need to replace some of these items, checkout our roundup articles on farmhouse sinks and garbage disposals.

Step 1: Establish that the disposal isn't the problem

If you haven’t already done so, the first order of business is to establish that the disposal itself isn’t the problem. We recommend turning it off and on a couple of times and then using an Allen wrench to turn the shaft of the grinding mechanism from the bottom of the exterior of the disposal. This is actually super easy to do and we show you how in the above link. If the Allen wrench can turn one way in a circle and the disposal sounds normal you can probably check it off your list of concerns and move on to the next likely culprit; the sink pipe. 

Step 2: The Plunger Method

First, unplug the garbage disposal. Then take a toilet plunger and plunge as you would a toilet for one minute, making sure the sink has enough water to cover the lip of the plunger and the plunger is covering the drain completely. This SHOULD free a clogged drain and your sink will likely begin draining on its own. If that doesn’t do the trick you can move on to step three. 

Sink Plunger

Step 3: Snaking and Other Considerations

Proceed with caution!

A couple of caveats for what you may need to do next. The pipe might require a snake to dislodge the clog. However, you may consider stopping here and calling a professional. Take a look at the underside of your sink to locate the P trap. For a double sided sink with a disposal the P trap should receive feed from both sides and be designed to be removed.

Assuming this is the case, one option here is to remove the P trap and clear the clog by reaching in or by running warm water through that section of pipe. Another option is to actually snake the pipe without removing the P trap. If you are sure your pipes are not corroded go ahead and insert your auger down the drain turning it clockwise until you can feel it reach the clog in the P trap of the pipe.

Now you are ready to turn it counterclockwise in order to bring the offending clump of gunk up and free the drain. If the pipes look corroded call a plumber so you don’t risk puncturing the pipe with the auger. If you locate the P trap but can’t seem to remove it and don’t have experience using an auger or snaking a pipe, the best thing to do is to call in a plumber. 


In summary, you want to first determine if the clogged drain is caused by the disposal being jammed (in which case you can see the tutorial on using a wrench to free a clogged disposal), or a clogged drain. Assuming the later is the case be careful and err on the side of caution. 

Never snake a pipe without knowing the state of your pipes and having some prior experience with plumbing. Doing so can result in damage to the pipes and a bigger, more expensive problem than you began with. Hope that helps! 

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2 thoughts on “Sink Only Drains When Garbage Disposal is On (What to do?)

    • Not sure I understand the question, Barry. I don’t think it assumes anywhere in the article that the drain pipes have a plug. Could you clarify? Sorry if I’m misunderstanding you. Thanks for chiming in.

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