Dishwasher Makes Sink Back Up:  Try These Fixes!

Picture this: You open your dishwasher, expecting clean dishes, only to find water sloshing back into your sink. 

Not the kind of surprise you were hoping for, right? 

There are four likely reasons for your dishwasher making the sink back up: clogged sink, dishwasher clog, garbage disposal glitch, or blocked air gap. You can quickly fix that by cleaning the sink drain, clearing dishwasher clogs, sorting out the disposal, and ensuring the air gap is clear. 

No biggie, though, for I’m about to tell you how to get rid of this reverse flow. 

You can get your dishwasher and sink under control in no time.

Let’s get started.

Reasons Why Dishwasher Makes Sink Back Up

Reasons Why Dishwasher Makes Sink Back Up

If you’ve seen it happen often enough, you’ve probably asked yourself, “Is it normal for the dishwasher to drain into sink?” 

Absolutely not. 

Your dishwasher’s job is to make dirty water disappear, not throw a curveball by sending it back up and causing an overflow. 

If you keep seeing the sink be like that, you probably need to do some serious cleaning. 

Let’s get down to all the reasons first before we go further.

Reason 1: Sink Drain Clog

Think of your sink’s drain as a highway bustling with water and bits of food. Over time, though, food, grease, and soap scum can create a jam. 

Water, looking for a way out, takes the detour and ends up in your sink. 

A small hiccup can slow down drainage, but a serious one can lead to water backing up into your sink – a not-so-pleasant surprise.

Reason 2: Dishwasher Clog

Even your trusty dishwasher can get a bit choked up. 

Tiny food scraps, grease, and maybe even a stray object can take up residence in its plumbing. 

These unwanted guests form a blockage, making it hard for water to flow freely. 

The dishwasher, struggling to find its way, resorts to sending water into your sink instead.

Reason 3: Garbage Disposal Issues

The garbage disposal can be incredibly handy, but it can suffer from a buildup of gunk and leftovers. 

A clogged disposal affects the whole system, rerouting dishwasher water into the sink. 

It’s like the disposal isn’t pulling its weight, leading to a watery mess.

Reason 4: Blocked Air Gap

Blocked Air Gap

The air gap – located around your faucet – acts as a shield against backflow. 

But with continuous use, it can become a collection point for debris, hindering its function. 

As a result, the dishwasher struggles to drain properly, causing water to back up into the sink.

How To Fix Dishwasher Overflow Into Sink

How To Fix Dishwasher Overflow Into Sink

Now that we’ve pinpointed the reasons behind your dishwasher’s sink antics,  let’s roll up our sleeves and get to work. 

The solutions are actually pretty basic – yep, it’s super easy for you to get things back on track.

Fix 1: Clearing a Clogged Sink Drain

Dealing with a clogged sink drain? No worries, let’s tackle it together:

  1. Turn off and unplug the garbage disposal to be safe.
  2. Put on gloves to keep things clean.
  3. Check the sink drain for any obvious clogs and remove them.
  4. Create a seal over the drain and use a plunger to loosen the clog.
  5. Pour half a cup of baking soda down the drain, followed by half a cup of vinegar. Cover the drain and let it sit for a while before flushing with hot water.
  6. If the clog persists, use a drain snake to break it up.
Note: If you’re thinking of using commercial liquid drain cleaners, be careful. They might promise a quick fix, but they can actually harm your pipes and garbage disposal. The more manual way I provided is a much safer option, even if you have to get your hands dirty.

Fix 2: Clearing Obstructions in the Dishwasher Itself

Clearing Obstructions in the Dishwasher

Is your dishwasher the culprit? Let’s sort it out step by step:

  1. Look at the drain hose connecting the dishwasher to the sink plumbing. Ensure it’s not twisted or blocked.
  2. Make sure any drain plug inside the dishwasher is removed. It’s usually taken out during installation.
  3. Turn on your kitchen faucet’s hot water and let it flow for a few minutes. This helps clear grease and food debris.
  4. If your dishwasher has a filter at the bottom, take it out and clean it. Built-up gunk can block drainage.
  5. Just like in the last fix- mix half a cup of baking soda with half a cup of vinegar.
  6. Pour the mix into the dishwasher’s bottom. This fizzing combo can break down stubborn residues.
  7. Run a dishwasher cycle with a dishwasher-safe cleaner to clear any remaining clogs or odors.
  8. After cleaning, run a regular dishwasher cycle with dishes to ensure proper drainage – see if the water comes up your sink again.

Fix 3: Resolving Garbage Disposal Woes

When your garbage disposal isn’t cooperating, these steps will help you get it back on track.

  1. Find the disposal unit under your sink.
  2. Make sure the power to the disposal is off.
  3. Use the disposal’s manual crank to move the blades and loosen any stuck stuff.
  4. Turn on cold water and the disposal to help wash away loosened debris.
  5. Drop ice cubes and a bit of coarse salt into the disposal, then turn it on. This helps scrub the blades clean.
  6. If your disposal has a rubber piece, take it out and clean it separately.
  7. Reconnect everything, turn on the disposal with cold water, and make sure it’s running smoothly.

Fix 4: Dealing with a Blocked Air Gap

Dealing with a Blocked Air Gap

Is Air Gap causing the headache? Here’s how to handle it:

  1. Find the air gap near your faucet.
  2. Take apart the air gap by removing its cover and inner cap.
  3. Give all the parts a good scrub with a bottle brush.
  4. Make sure the drain hose isn’t kinked or clogged.
  5. Put the air gap back together carefully.
  6. Run water through the air gap to ensure it’s working properly.


How do you know if your main drain is clogged?

If water’s acting weird in multiple places – sinks, showers, or making gurgling sounds – that main drain might be acting up.

Why is my sink gurgling and backing up?

Well, that’s usually a sign something’s blocking the pipes, causing the sink to act up.

Can you run dishwasher if garbage disposal clogged?

It’s best not to. A clogged disposal can lead to a backed-up sink and dishwasher mess.

Why is my sink backing up into my dishwasher?

This often means there’s a plumbing hiccup, like a clog or blockage somewhere. You’ll want to sort that out pronto.

Final Thoughts

Now you’re equipped with the know-how to keep your kitchen plumbing in check. 

It’s all about simple steps and a bit of DIY magic. 

So, go ahead and tackle those clogs and backups. 

And always remember, a little maintenance goes a long way!

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