Bathroom Lav Clogged

[Ben H.]

Interesting problem here. Got an old house with a bathroom lav that drains slowly after a while, give it some time (a lot of time) the water drains out and all is well. I've had the line snaked up to 20', you can hear the shower running and the toilet flushing through the trap when it's opened, the trap is cleaned and I've plungered it real good.

To my knowledge it is vented, maybe not properly, and the line is clean. After pushing a plunger on the drain it will suck water back up into the bowl, when I stop the plunger the sucked up water will drain back to the original spot...

Pretty confused about this, any help or direction would be great. Wanting to avoid cutting the wall if possible, thanks!

 

[Cacher_Chick]

Plungering will not do any good unless you have a way to block the overflow and vent. I usually take the trap and trap arm off and snake through the sanitary tee in the wall, that way I can make sure the snake is going down the drain instead of up the vent.