Bathroom sink will not drain.

[sean20025]

There is not a vent on the drain line. I snaked the pipe all the way down to the trunk, link was clear. This is a small bathroom sink that drains VEEERRRYYY slow (1-2 hours) for half of a sink-ful.....

Please help. See attached picture....



Thanks!

[Nestor]

I expect what's happening is that when you pull the drain plug, all the air that was below the drain plug ends up suspended as bubbles in the mixing (moving and stagnant) water in the S trap. And, I expect that as the entire S trap fills with water, those air bubbles would accumulating at the top of that S-trap to form an air pocket that pinches off the area available there for for water to flow through.

I make my own beer/wine, and that often happens at the top of a siphon tube when siphoning the beer or wine into a different container. And, as you've learned first hand, depending on the size of that air pocket it will reduce the rate of beer flow, anywhere from a little to a lot. Sometimes, if it were any slower, you'd lose the siphon.

I'd just rotate that tee and connect a p-trap to it (not an S trap), and connect your air admittance valve to the top of the drain pipe (where your S trap is connected now). Your sink should drain properly then.

Hope this helps.

[pushkins]

S traps which is what you have there, should never be used in plumbing, even though the plumber added a studor vent

A simple solution would have been for the plumber to bring the floor pipe all the way up with a vent on top of it, T into it the vertical line and make the trap connection with a standard P trap.
The studor valve must be remain downstream of the trap and should be as high as you can get it inside the cabinet, right up under the vanity top or at least above the vanity bowl overflow.

[LazyPup]

The line has been snaked and they are certain that its open and there is no way possible for the air in that line to keep the water suspended so let us consider the next obvious problem area.

The line was most likely snaked from the trap down.

Remove the lever for the stopper, pull the stopper and remove the hair clog on the stopper lever.