When the garbage disposal is on, the water goes into the other sink and never goes down the drain.

RichardBondMan

I am no plumber but there is one that reads and answers questions like this, he's very good, experienced but until he does answer, try this, 1) cover the drain that you state the water flowing down not letting air, debris come back out of the drain while you 2) use a plunger over the top of the drain that the disposal is connected to and plung that drain with the disposal on. do not keep the disposal running for long without water flowing thru it. Hope this works. For safefy, dont put you hand down the drain unless you disconnect all electricity to the unit before hand. Some of the more expensive disposals have a reverse switch which might help in unclogging the disposal.

speedball1

You have a blockage in the lateral (horizontal), drain line in the wall. The solution is to remove the "J" bend from the trap and send a snake up into the wall and 6 feet beyond. You will hit a bend about 8 inches in but work your way around it and you're home free. Good luck, Tom