Bathtub Drain Gurgles When Toilet Is Flushed (Fix It Now!)

Does your bathtub drain gurgle when toilet is flushed? Nothing is annoying than flushing your quiet flush toilet only to hear your bathtub gurgle.

If you’ve been experiencing this problem, then there’s no need to panic because there are simple fixes to you can implement right now to make the problem go away instantly.

In this guide, we shall discuss the reasons why bathtub drain gurgles and some of the different ways to fix it.

Why Bathtub Drain Gurgles When Toilet Is Flushed

Faulty Sink Vent

A fault sink vent is a common source of gurgling sounds. The sink vent helps to remove any water and air from the drain pipes, allowing the plumbing to function effectively. If this vent gets clogged or broken, your drains may begin to gurgle.

Run water through the faucet and listen for gurgling sounds to test this. If you hear these noises, it is possible that your sink vent is clogged and must be cleaned. You may use a plumbing snake or manually empty it to accomplish this.

Clogged Sewer Line

If your bathtub drain gurgles whenever you flush your toilet, there is likely a clog in the central sewage system. This may result from tree roots, garbage accumulation, or other things trapped in the pipe. You’ll need to hire a licensed plumber to clear the obstruction and restore appropriate drainage.

Narrow Drain Valves

If you have gurgling drains when flushing the toilet, it’s likely the drain pipes are too narrow. This might generate a suction that draws air from the sewage system and cause the drains to gurgle. Some of the waste from the toilet will undoubtedly stick to the pipe walls.

This waste tends to decompose over time, resulting in a solid blockage. This will not physically clog your pipes but significantly narrow them. When even a small amount of water enters your bathtub drain, pressure develops, and air gurgles.

If you’re fortunate, your plunger may be able to dislodge some of the solidified debris and enlarge the pipes. Use rubber plugs to seal the drains of your bathtubs, sinks, and other fixtures. Thus, your whole plunging power would remain within the pipes.

 Using a toilet auger is recommended if the gurgling remains after three to four rounds of plunging. You can also use a toilet auger to clear the clogs. It works similarly to a standard drain auger but is fitted with a more extended arm to push the wire deeper. However, be careful when using the auger so as not to scratch the toilet bowl.

Plumbing Vent System

A problem with the vent pipe is among the common causes of gurgling sounds from the bathtub drain. The vent pipe facilitates the free movement of water in the plumbing system. Water won’t flow properly if there is a blockage or a leak.

Air fills plumbing pipes if no water is available. All plumbing systems are equipped with ventilation mechanisms that exhaust air through the roof. If the plumbing vent system is obstructed, bathroom drains may gurgle. The plumbing pipes in a bathroom are all linked to one system.

When a fixture in the plumbing system becomes clogged, you will notice a gurgling sound.

Rusty Cast Iron Pipes

Before the introduction of PVC and ABS and PVC pipes, cast iron was commonly used in plumbing systems. Cast iron, unlike its successors, is prone to rust and hard to cut without assistance.

If your home was constructed before the 1980s and you still have cast iron drain pipes, it is likely that they are rusted and should be replaced. There may be some leaking at the joints or in the gaps of the pipes. In this situation, you should contact a professional plumber to replace them.

Air Coming out of the drain– when the vents are clogged, air forces itself through the drains. This creates a pressure difference resulting in gurgling noises.

The air in– bathtub is equipped with air vents that controls the amount of air that flows through the pipes. These vents can get closed trapping in the air within the piping system.

The air inside the water causes gurgling in the bathtub.

P-Trap– bathtubs are equipped with P-traps in their piping system designed to keep the pipe with a specific amount of water.

If the bathtub lacks P-trap, air will freely flow when the toilet is flushed, creating gurgling noise.

How to Fix Bathtub Drain Gurgling Noises

Now that you know the different causes of noise when the toilet is flushed, lets have a look at some of the different ways to fix this problem.

1. Pump Air Out Using a Plunger

One of the reasons that cause a bathtub drain to gurgle when flushing the toilet is air stuck in the pipes. Using a plunger will remove the air in the pipes, drains, and even unclog the toilet.

This is an easy and quick method to sort your plumbing issue without involving a plumber. You only need to purchase a few things like duct tape and plunger, and you are good to go.

How to pump air out

Use duct tape to close the drains. Cover the drains and pipes to prevent air from getting in.

This process ensures that the force of the plungers stays within the pipe. Ensure the bowl of the plunger is totally submerged in water before you begin the process.

Start plunging for a few minutes, then flush the toilet and listen to whether there is the gurgling sound. If it’s still there, start plunging again.

Plunging removes air or any other obstructions stuck in the drains or the pipe.

You can use Neiko 60166A Toilet Plunger for this process.

2. Check the Venting System

If the problems still persist even after continuous plunging, then you need to take a look at your venting system.

Due to the location of the venting system (the one on the roof), it means leaves or dirt may get into the pipes and become a problem.

You need to continually clean the vent to remove the dirt and allow air to go through easily.

Cleaning the pipes is not hard, but it may require a bit of effort, which is worth it considering the nuisance that clogged vents bring.

You will need your hose pipe or any other material that can force water through the vents and a plumbing snake.

The process involves:

Climbing up the roof and check for any blockages on the vent’s screen. Remove the leaves, then wipe off the screen, and ensure its clean.

Then using the hose pipe, force water down the pipe to remove any obstructions. If you notice water backing off, then there is a blockage.

Some blockages may be stubborn and hard to reach, so you will need a FlexiSnake FSMPD Drain Millipede plumbing snake to remove them.

Simply insert the plumbing snake into the vent’s pipe until you reach objects blocking it.

Then work the plumbing snake back and forth to altogether remove the clog.

Using the hose pipe run water in the pipe to check whether the problem is solved if not, repeat the process again.

A plumbing snake might be quite challenging if you have never used it before, so you might need someone with the knowledge.

3. Increase the Diameter of the Pipe

Bathtub Drain Gurgles When Toilet Is Flushed v_1_1

Another possible solution to your gurgling problem is increasing the diameter of the pipe. Extra toilet paper can be a problem to a smaller pipe.

So, you need to increase its diameter to ensure that waste flows through without clogging. Most toilet drain pipes are 3 inches in diameter; raising it to 4 inches allows more waste to pass through.

You will need to replace the existing pipe with the 4 inches. The process is not laborious if you are ready for the work; it’s actually an excellent DIY project that saves you a lot of money.

Increasing the diameter of the pipe is not only a “now solution” but can also benefit you in the long run.

You will need the help of a professional because fixing the pipe require technical knowledge.

4. Use Chemical Solutions

You can also use chemicals to deal with bathtub gurgles when the toilet is flushed. Certain chemicals can help clear the problem and give you peace of mind.

There are Chemical solutions that you can easily make at homes, such as a drain cleaner, which consists of water, baking soda, and vinegar.

All you need to do is boil a lot of water, almost a gallon. A lot of water ensures there is enough force to remove the clog. However, ensure the water is not too hot because it may damage the toilet’s porcelain.

Pour your vinegar and baking soda into the toilet to remove the clog. The combination of the products creates a solution that is effective enough to dissolve the clogs.

However, in the case of clogs, such as a rock or toys, the solution may not work.

Once you have poured the solution, pour the hot water into the toilet, starting from the waist level. The hot water ensures that the clogs are pushed out of the drains.

Lastly, allow the mixture to stand still until morning. This will give it enough time to dissolve the clogs and push them down the drain.

Remember, this method will only work on clogs from organic material. Therefore, if you still hear the bathtub gurgling, then the cause is a much bigger object.

You can also purchase a drain cleaner such as Green Gobbler Drain Clog Dissolver if the problem is not hard clog. The process is simply pouring in the drain cleaner according to the manufacturer’s instructions

Ensure you allow the solution to stand still for some hours before you use a plunger.

Also, ensure you open windows to allow air to flow in since the chemicals can be quite unbearable.

5. Use a Coat Hanger to Remove Clogs Near the Drain

Another material to help you remove clogs is a coat hanger. This may seem like a strange method, but it actually works.

The steps involve:

Straighten the hanger, then cover the end using a rag to prevent it from damaging the toilets’ porcelain.

Then guide the straightened hanger, which is wrapped down the drain until you reach the obstruction.

Then twist the hanger severally to break the clog and remove it.

Finally, flush the toilet to push the broken clog down the drain to the sewer.

Remember, this method only works for clogs that near-reach. You will need a plumbing snake for the hard to reach clogs.

6. Call a Plumber

If you have tried all the methods, but the problem still persists, then you may need to call in a plumber.

A plumber will inspect your bathtub, drain, and the toilet and know what needs to be fixed.

Final Thoughts

Above are some of the best fixes on bathtub drain gurgling. However, you should note that gurgling drains may be a sign of a bigger problem with your piping system.

Regular maintenance will help prevent this problem and other related.  If you’re unsure how to fix this problem, please consult a professional plumber to help you out.

6 thoughts on “Bathtub Drain Gurgles When Toilet Is Flushed (Fix It Now!)”

  1. I have two toilets tied at a ‘Y’ on first level . When I flush , the tub drain gurgles, if I flush 3 times the poop comes up in tub. GROSS! Can a clogged vent on roof cause this ?

  2. Hi- I live in an old house. First, when I emptied to bathtub, the water in the toilet would recede. I called roto rooter and they found lots of roots in the line leading out to the city pipes.
    Now, when the tub empty’s the toilet water does not recede but when I flush the toilet, I hear noise in the bathtub and sink for a short time.
    Roto rooter says I may need to reline the basement line leading to the city line with fiberglass.
    Could there be a different issue?

    • Hi- that’s what rotorooter told me and the guy did a quick video of the line but didn’t explain what I was looking at. He said about 18,000.00$ would fix it. I’m not sure that is the problem because the vent on the roof is what other people have told me as well. I would have to hire someone to go up on a steep roof. These are old systems of course but I also think that the guy from rotorooter is looking for jobs as well.


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