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Plumbing in the Home/toilet girgles when washer drains


Why would my toilet bubble when my washing machine in another room drains??
Thank you,

ANSWER: Susan,
The reason is improper venting. Plumbing systems need air to function properly. When a large volume of water is sent down a pipe, as in flushing a toilet or draining a clothes washer,
the water pushes the air in the pipers down the line ahead of the water, because there are traps on the drain line, the  vents give the air someplace to go and allow the water to drain. Once the water pass by the vent pipe, it works in reverse allowing air back into the pipe to replace what was pushed out. It stops any type of syphoning and breaks any vacuum condition.
The placement of these vents is very critical in that they must be a located close to the point where water is introduced into the piping. Too far away and they won't work. They must also be sized properly. SOOOO what you have is air being forced through the toilet trap and causing air to bubble into your toilet because it can't get out  via the vent. It is either , too small or too far away or plugged. Again,because it is being forced into the drain as opposed to flowing due to gravity, amplifies the condition.

---------- FOLLOW-UP ----------

QUESTION: If it is plugged, where would it be plugged? Is the vent near the place where the water shuts off outside? This just started recently, the toilet bubbling, we have been here 15 years. Plugged sounds like this could be the problem.

ANSWER: The vent for the toilet is or should be  at least a 3" line that goes up and through the roof.
I have seen birds nests and debris in them. I would first have the main line checked and a
If you have a basement or access to a clean out close to the toilet line then you can try rodding out the line from there. If you are going to hire someone to  rod the sewer lines, make sure the do all the lines from the toilet all the way out to the street.( public system)

If you are on a private septic system then it is quite possible the baffle in the tank is plugged is causing the gurgling. Most times having the septic tank pumped out will do the trick
just be sure they clean the baffles too.

I have had customers put a garden hose down the vent from the roof to flush them clean, I don't recommend this . It is dangerous and may lead to water damage in the house if the vents are not water tight.

---------- FOLLOW-UP ----------

QUESTION: Yes we are on septic-the toilet near the septic system has had water on the floor in the back-seems like it happens when I wash clothes. I called a plumber to see why the toilet was leaking, he could not find any leaks-so we were puzzled. That is not the toilet that is gurgling, that one seems to be where the washer drains, when the washer drains the kitchen sink gurgles and the toilet gurgles, but not the one in the master bath near the septic where there is water on the floor. Could it be in the wall of the toilet near the septic? I will have the baffles checked. I did not tell the plumber about the gurgling. Thank you for all your help!

My gut feeling is you have an issue with the  main leading to the septic tank. I would have it pumped before I did anything else and be sure they( septic cleaners)do a thorough job when they pump it out. Good Luck and I hope I helped you get a better idea of what might be wrong.


Plumbing in the Home

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Jay Nicholas


Plumbing & Heating (warm air, hot water & steam heat)


40 years in the business, 40 years as a lic. master plumber in NY State. Retired

Graduated Magna cum laude at the School of Hard Knocks

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Commercial, residential and light industrial. You name it ...I have probably worked on it

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