What does it mean when your toilet gurgles while taking a shower?
Unknown to most homeowners is the fact that your toilet, shower and bathroom sink drains are interconnected and can therefore be in communication. They share the same drainpipe and vent stack.
If your toilet gurgles/bubbles when you shower, it is a sign of a clogged main drainpipe or vent stack. As the shower drains, air will be trapped in the drainpipe or a vacuum will be created which will siphon out water from the toilet bowl and hence the gurgling.
The solution for a toilet that gurgles while you are taking a shower is either unclogging the main sewer line or the vent stack. A plumbing snake is a fantastic tool for unclogging both the sewer line and the vent stack.
It is important that you fix a gurgling toilet as soon as reasonably possible. If you are dealing with a clogged main drainpipe, wastewater will continue piling up in the drainpipe and after a few days sewage will start backing up from your drains.
How Does a Blocked Drainpipe/Vent Cause a Gurgling Toilet?
A vent stack is the vertical pipe which runs from the main house drainpipe through the roof of your house. It has 2 main functions.
- It provides a way for sewer gases to exit the drainpipe. If the vent stack is clogged, you may also experience a sewer gas smell in your house, as the gases will be forced out of the drains.
- It introduces air into the drainpipe.
In order for your fixtures to drain fast enough, there needs to be air in the drainpipe. It is the same thing as when you want to drain water out of your water heater.
You would need to open one hot water faucet to introduce air into the tank and hence faster and smooth draining.
But why can’t air just enter the drainpipe through other drains like the sink drain? Well, if you look underneath your sink, you will notice that a part of the pipe is bent to look like a U.
That is by design and not accident. Every fixture in your house has that bend. You will also notice your toilet has it, and that is why it is able to hold water at the bottom of the bowl.
The U-bend is known as a P-trap. It is always full of water. The water acts as a barrier which prevents sewer gases from coming out through the drain, but instead exit through the vent stack.
When the have a clogged vent stack and you drain your shower, air will be trapped in the drainpipe creating what is known as negative air pressure. The air will force its way out through the toilet or sink drain and hence the bubbling.
Another thing that can happen is that when you drain the shower, a vacuum will be created inside the drainpipe. Since a vacuum cannot exist, it will suck the water from the toilet bowl and hence the gurgling sound you hear from the toilet while you take a shower.
This is the same thing that happens if you have a blocked main drainpipe. Each of your fixtures (sink, shower, toilet etc.) has its separate drainpipe which is connected to the main house drainpipe.
The fact that the toilet gurgles when you take a shower indicates that the clog is sitting somewhere in the main drainpipe. You may have a partial clog or a fully clogged drainpipe.
It is difficult to tell if the clog is in the drainpipe or vent stack since in both cases your shower/tub will be draining slowly and the toilet will most likely have a weak flush. A partial clog will easily develop into a full clog.
Just like with a clogged vent, when you have a clogged drainpipe and then you take a shower, air will either be sucked in or out of the drainpipe. A gurgling toilet indicates that air is being sucked in while a bubbling one indicates that air is being forced out.
How to Fix a Gurgling Toilet
There are 2 ways to fix a toilet that gurgles or bubbles when flushed. Either clear the vent stack or unclog the drainpipe.
The following are the ways to fix a gurgling toilet:
1. Plunge the Toilet
A toilet plunger can and will dislodge light clogs. In order for you to plunge your toilet properly, you will first need to do 2 things:
- Select the right plunger. There are 2 types of plungers, flat-bottom plungers and bell-shaped plungers. The correct toilet plunger is the bell-shaped plunger. It allows for the creation of a tight seal around the toilet bowl opening.
- Seal off other drains. Plunging with the tub/shower/sink drains still open will simply mean that pressure generated by the plunger will escape through those drains. Use duct tape to seal of the other drain openings without forgetting the overflow drain openings.
Make sure you have enough water in the bowl to cover the entire plunger cup. Introduce the toilet plunger and engage it around the opening at the bottom of the bowl.
The first plunge needs to be a gentle one, to make proper contact between the bowl and the plunger, and to also avoid water from splashing on your face.
Plunge aggressively for a few minutes. To check if the clog has been dislodged, dump a gallon of water down the shower drain and listen carefully if the gurgling stops.
2. Snake the Drain
A drain snake is in my opinion the best tool for unclogging drains. Although there are special toilet snakes known as a toilet augers, those are only 4 to 6 feet long and may not be very helpful for a clog in the main drainpipe.
What you need in this case is the drain snake rolled on a drum, or better still a motorized drain snake. Motorized drain snakes can reach up to 100 feet and the fact that they are electrically powered makes them very efficient in breaking down clogs.
You can either feed the drain snake through the toilet bowl outlet or through the shower/tub drain as shown in this post.
The only risk with drain snakes is that if you are not experienced in handling them you can badly damage your plumbing, resulting in even more expensive repairs. If you don’t feel comfortable snaking the drains yourself feel free to contact a plumber.
3. Unclog the Vent Stuck
Plumbing vents should be covered with a protective screen to prevent it from being blocked by debris. Without it, leaves, dead rodents, birds, nests, snow and other types of trash will clog it at some point.
The good thing is that clearing a clogged vent stack is not that hard. Climb to the roof of your house armed with a garden snake and/or drain snake.
- Check if there is any trash at the top of the vent that you can easily remove with your hand. Pull out as much of it as you can.
- Stick the garden house and use to try and dislodge any clog that you may encounter by continuously probing it.
- Have someone on the ground turn on water to the garden house. The weight of the water and the garden hose probing may be enough to dislodge the clog. If the clog will just not budge, upgrade to a more powerful tool. The drain snake.
- Feed the drain snake down the vent stack until you encounter resistance. Start cranking the handle until you go through the restriction.
- Continue pushing the snake down just in case there is another clog.
- When you are certain there is no any other clog pull out the snake and climb down.
And basically that is how to fix a toilet that gurgles/bubbles when you shower or drain the bathtub.
4. Call the Plumber
If you are not successful on your own or if you don’t feel very comfortable undertaking the task, you can always contact a reputable and professional plumber. Plumbers will have come across this type of problem many times and will know exactly what need to be done.
Just know that calling a plumber will cost you upwards of $100 or even way more if they have to run a camera down your plumbing. It is however a small cost compared to attempting to fix the problem on your own and end up damaging the pipes.