How to Fix a Gurgling Kitchen Sink

If you hear a gurgling sound from your sink while the water is running or your dishwasher or washing machine is draining, there are a few things you can do to remedy the issue. Luckily, it’s generally an easy repair. Today, we’ll be walking you through how to fix a gurgling kitchen sink in five simple steps.

Why Does My Sink Gurgle?

Before learning how to fix a gurgling kitchen sink, it helps to know what actually causes sink gurgling in the first place.

  • Unvented drain or a blocked vent pipe: Imagine you’re holding a bottle of water. When you flip it over, and the water starts flowing out, air bubbles rise in the opposite direction, creating a deep gurgling, sputtering sound.

    However, when you poke a hole in the bottom of the bottle, the water will come out smooth with an uninterrupted flow. That’s how your plumbing is supposed to work. Your vent pipe is like the hole in the bottle. If you don’t have one, or it’s blocked, gurgling can result.  
  • Damaged pipes: Similar to a blocked vent pipe, damaged pipes upset the proper flow of water and air within your plumbing system.
  • Clogs or dirty pipes: Food, grime, and other waste material can build up in your drain or pipes and cause a blockage, which can lead to gurgling. The blockage doesn’t necessarily have to be in your kitchen sink drain. Though toilet gurgling is more common in deeper system blockages than sink gurgling.

5 Ways to Fix a Gurgling Kitchen Sink

There are 5 different repairs that typically resolve kitchen sink gurgling. Identifying which sinks in your house are gurgling can help you choose which option to try first. If the gurgle is only in your kitchen sink, the issue is likely in the drain or pipes of that sink.

Start with your P-trap. If your bathroom sinks or other drains in the house are also gurgling, you might have a problem with your main vent or a mainline clog. As the main vent is easier to fix, start there.

1. Flush Your Home’s Main Vent

Your plumbing system’s main vent is very likely on your roof above your primary bathroom.  To clear blockages in the vent that may be causing gurgling, you can shoot water with a considerable amount of force into the vent opening or rent a sewer auger. Note that if you opt for an auger, it should reach all the way to your sewer.

While you can clear a main-vent clog yourself, a professional is generally recommended. As the repair requires roof access and high-pressure water or specialized equipment, it can be a complex and even dangerous task.  

2. Fixing the P-Trap

Under your sink, there is a U-shaped pipe commonly called a P-trap that holds water that acts as a barrier so that sewer gasses can’t waft into your home. If the P-trap is an improper distance from the vent and the drain, it creates a vacuum that siphons water away from the P-trap, and gurgling results.

The total length of all tailpieces, arms, and fittings between your drain and the P-trap should be 24 inches or less. For example, if you have a drainpipe that’s roughly 1.5 inches long, the vent must be 3.5 feet from the lower part of the trap. If yours is closer than that, you’ll need to modify the piping to create more distance.

3. Fixing an Air Admittance Valve

Some drains have an air admittance valve instead of a vent. In a conventional setup, all the plumbing fixtures connect to a vent that passes up through the roof and allows air into the drain to replace water as it disappears. In some systems, this vent is replaced with an air valve just after the P-trap. If this valve is broken or clogged, air pressure in the system is upset.

A clogged or broken air admittance valve is very easy to replace—you can unscrew and re-screw them by hand. They cost $10 to $20 at The Home Depot, and they’re good for 20 to 30 years.

4. Flush the System

If your main vent or air admittance valve and P-trap all look good, before you try more complicated repairs, we recommend trying the simplest fix—run water. Just turn your water on hot and let it run for about 15 minutes.

There may just be a slight clog somewhere in the line, and a quick flush can solve the issue. If you have an older home, it may also be worth hiring a professional to clean the system.

5. Clean the Drain

If flushing the line doesn’t work, the next step is to clean your drain. Even if you are diligent about using a screen, some food debris will inevitably make it down your kitchen sink. Especially in homes with well water, mineral build-up can also be an issue.

Place a bowl or pan below the P-trap and remove it – be aware that there will be water inside. Dump the water and anything else inside into the bowl. In addition to its sewer-gas-blocking ability, your P-trap also catches things before they can pass into – and potentially clog – your pipes. Coincidentally, they can also be a lifesaver if you lose something like a ring down the drain.

Once empty, clean the trap and replace it. You can use a cheap nylon brush to get the inside good and clean.

Is Your Kitchen Sink Still Gurgling?

Is Your Kitchen Sink Still Gurgling

If you try all the above and your kitchen sink is still gurgling, your best bet is to call a professional.

It’s possible there is a blockage further in your pipes or an installation error you overlooked somewhere. Either way, the repair is likely beyond simple DIY tasks. Whatever you do, don’t ignore the problem if you can’t fix it.

Sink gurgling might seem like a small issue, but it’s almost always a warning sign of an underlying problem just waiting to turn into a big, expensive mess.

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