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Vent pipe leak sound

Whenever we shower or use any appliance in the two adjacent bathrooms we hear a consistent sound that comes from a vent pipe diretly over head the bathroom that sounds like a drip. The drip intervals are very consistent at about 10-15 seconds apart. We will hear the sound for about 15-30 minutes after use of the sink, water closet, or shower. Extremely annoying when trying to sleep.

I replaced the ceiling and found no evidence of water damage.
I have identified the spot in the vent pipe, along a horizontal run, that the sound eminates.

I do have access to this pipe as it is in the attic.

Any ideas as to what causes this sound and how to eliminate it.

Re: Vent pipe leak sound

I have exact same problem as you. I have a new house and it's been driving me crazy for over a year. Any luck on solving your problem?


Re: Vent pipe leak sound

If you have a horizontal run for the vent pipe in the attic the sound you hear may be from moisture accumulated in the pipe being drawn down after using a plumbing fixture.

This would be caused by air being drawn into the vent from outside .... since that's a primary role of the vent .... to provide air behind water for draining. Each time the water flows down the drain from the tub/shower , sink or toilet air from the vent pipe is drawn in to aid in moving that water down the drain.

Same principal as putting a straw into a glass of water. Cover one end of the straw and the water will remain in the straw .... uncover the end of the straw and the water will drain out.

There can be moisture accumulation in the horizontal ( flat) run of a vent pipe in the attic from condensation forming inside the pipe from the warmer moist air/sewer gas condensing in a cooler attic space.
Another source of moisture accumulating would be from rain outside. Remember the vent outside is wide open to the elements and when moisture outside finds it's way down the vent pipe it will accumulate in the (flat) horizontal section of the pipe.

You might consider changing the horizontal (flat) run of the vent to a sloped run .... allowing any moisture from condensation or entering the vent to drain instead of accumulating.

Just a thought. :)

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