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Washer pushes sewer gas through Kitchen sink

Whenever my washing machine drains, it blows sewer gas out of my kitchen sink. The house is single story with a single sewage pipe running from the rear of the house to the middle where it exits. The washing machine is the last thing on the line (rear of house)and has a p-trap. The kitchen sink is the next after the washer. Sink has a studor(?) vent on it as well as a P-trap.

Any idea why this is happening? And more importantly, how can I fix it?

Re: Washer pushes sewer gas through Kitchen sink

Another name for the Studor vent is air admittance valve. Studor is just the brand name everybody knows. And that may be worn out. there is a ruber diaphram inside of the valve that allows the air to go one way, but not the other. this may be wore out and needs to be replaced. a new Studor valve, even made by Oatey will cost about $15-25 and you can do it yourself. It should have threads on the end of the vent pipe coming up where you can grab it and screw it off. it will be as tight as a jar of pickles, but once it gets going your in luck.

now, as far as sewer gas being blown through the water seal in the kitchen p-trap. WOW. try running water at the same time the washer is going. Also, does the kitchen have it own vent? you said it was at the top of the line, so I am assuming you understand the theory of waste and vent. otherwise you do need to make sure the vent for the kitchen sink is open. another way is to fill the sink with water. Also, do you hear a sound like bubbles being blow through a straw and then the smell? that would indicate what you are saying is true.

Try a new Studor valve first, then check the kitchen sink vent. Process of elimination.

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