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LaurienMatt · Nov 26, 2008, 04:41 PM

Hello all..

We recently moved into a new house & are having an issue with our kitchen double basin sink... It has the branch for the dishwasher(which is not yet hooked up)... Our sink was draining fine until I attached the hose for the drianage of the dishwasher... After attaching the hose, the sinks back up...

Any help on this would be greatly appreciated... If you need any more info, just let me know...

Thank you in advance for all your help...

truck 41 · Nov 26, 2008, 05:16 PM

Hello, Does your sink have a disposal? Or is it a branch tail piece. Either way it shouldn't cause your drain to back up, check to see if there is a cleanout on the wall for the drain, and if its on the outside of the wall carefully unscrew the plug to make sure its not the drainline that's the problem. If the cleanout is under the sink carefully unscrew the plug. If it is the drain you'll have water start coming out as you unscrew the plug, get a container ready in case you need to cach the water from the drain in the wall. You can start by checking that then get back to us and let us know what you find. If the drain is plugged then you can rent a snake to snake out the drainline yourself or call a plumbing co. to take care of the problem. Is your house under warranty? Or check your homeowners insurance they may cover the cost to get the problem repaired. Goodluck ----Zeke---

LaurienMatt · Nov 26, 2008, 05:30 PM

Currently there is no no disposal, the "Y" shaped branch piece is going to be used for the drain of the dishwasher.. When the dishwasher hose is not attached to the "Y' shaped portion of the drain... it drains fine.. but when I connect the hose for the dishwasher... the sink backs up almost instantly... It almost seems if the drain would need some sort of breather... Aren't drains usually a closed system?

I apologize if my terminolgy is poor...

Any further help is greatly appreciated...

EPMiller · Nov 26, 2008, 07:07 PM

Sounds like your sink has no vent. When it drains well, is that dishwasher arm of the tee open or plugged? If open, just cap it with some plastic and a rubber band. If that causes the sink to back up, then you are going to have to get the drain vented or install an AAV (air admittance valve).

speedball1 · Nov 27, 2008, 07:30 AM

Hi Laurien,
Do you have a "S" or "P" trap on your sink? (see images) Back to you! Tpm

LaurienMatt · Nov 27, 2008, 08:02 AM

After reading your responses & tinkering with it a little more... I am closer to success... The last question I have is... I assume that the branch for the dishwasher is to be located below the "s" trap? I have gotten the drain to drain faster.. but when I have the hose connected for the dishwasher & a full sink of water to drain, the water wants to back feed up the hose for the dishwasher... I assume that the "AAV" will alleaviaite this problem?

Thank you very much to alll that have responded & I wish you all a very happy Thanksgiving!!

Laurie & Matt

speedball1 · Nov 27, 2008, 08:40 AM

Hi Laurie and Matt, HappyThanksgiving!

I assume that the branch for the dishwasher is to be located below the "s" trap?

You assume incorrectly. The "Branch Tailpiece" (see image) Is just that. A tailpiece that installs under the sink drain and above the trap.

I assume that the "AAV" will alleaviaite this problem?

Replacing the "S" trap with a "P" trap and AAV, (see image) and venting your sink will certainly make it drain much better. Good luck and thanks for trating my reply. Tom