So I just finished a total gut and redo in the kitchen. Everything is working perfectly (drains nice and clean, etc.) and I was happy of a job done right.

My wife comes to tell me the sink is backed up and draining VERY slowly. I turn on the disposal and WHAM! The sink is empty again.

I can only make this happen when cleaning big pots and then dumping loads of water suddenly. Is that just a reality of the situation, or did I do a major boo boo in the venting?

I replaced all the pipes (both vent and drain) with 2" PVC so I'm sure they are open (at least to the basement where they join the main waste line to the sewer). I had a similar (but VERY regular) problem before the kitchen redo, so this is really annoying if I didn't actually solve it.

Help? Matt

My disposal does the same thing. When there is lots of water in the sink it drains slowly unless the disposal is turned on. It gets much slower when there are food particles in the disposal. Sometimes it is good to get Roto Rooter or the equivalent (rent a sewer machine) and clean those disposal lines out if possible (if you think it may be blocking up on you... I just did this and things are running a bit faster).

The disposal has a holes all around the outside and an impeller that beats on any solid material in the disposal until it is small enough to go through the holes. With or without the disposal running, water goes down into to the disposal and out the same holes. If the water has solids to big to pass the holes, the solids build up and plug the holes. Turn the disposal on, and the solids are beat down to where they will go out the holes with the water behind.