Q&A / 

Clog Free Vent Pipes

Dear Tim: We have a bizarre problem that nobody understands. They pump the sewers in our street with some contraption called a VAC. Each time they do this I get water bubbling out of my toilets and a terrible sewer smell. Nobody including public works can explain why this is happening. The only toilet not affected is one in the basement that is on its own pump. The worst toilet is on my first floor. They advised me to put Saran wrap on my toilets. The suction is so great it pulls the Saran off the toilet. If you can shed light on this problem I will be forever grateful. The house was built in 1927 and the bathrooms have all been updated. Thank you. Laura, New Jersey

Dear Laura: I know exactly what is happening. The vent pipes for your plumbing system that extend through the roof are clogged or almost completely clogged. Another possible answer is any number of fixtures in your house are not vented properly.

When that vacuum truck is sucking out debris from the sewer line, any sewer tap between the vacuum and the sewer clog is subject to enormous suction forces. If the plumbing vent pipe is wide open, it can supply the needed air to satisfy the vacuum truck. But if your vent pipes are clogged or are not letting in enough air, the vacuum suctions out the water from the traps in all or several fixtures. Once this happens, the water seal is broken and sewer gas can enter the house.

Place a garden hose up in the vent pipes of your roof and turn the hoses on. Have someone help you inspect the inside of the house for leaks as the water is running. Vent pipe joints can leak in rare instances and it is possible for a vent pipe to crack. If the vent pipe is in good working order, the hose water will run forever without overflowing on the roof and there will be NO LEAKS indoors.

Author's Note: We've received other emails with similar problems or questions. Here's one from Brian R. of Dearborn Heights, MI, regarding a clogged vent pipe.

"Bathroom sink drains really slow. Pipes are clear. Professional snaked. All types of cleaners. This sink will just not drain properly. I hear gurgles in the pipes when the shower is on or draining so I am thinking its a vent problem. How do I know if it is a vent problem and if not, how do I figure out what the problem is?"

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One Response to Clog Free Vent Pipes

  1. hello,
    recently our toilet's have started bubbling, we checked our vent pipe and it has a screen over it and is not clogged but it also vents into our eves of the house can you help, my sinks and washing machine all drain ok we have no sewer backing up into the house but when I am using the shower or running anything in the house water starts bubbling in the toliet's

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