kitchen sink trap problem

[kanezfan]

I think I already know why I'm having this problem but I wanted a second opinion from someone who knows for sure.... We remodeled our kitchen and moved our sink over a couple feet. The new sink is deeper than the old one, so after I installed a new drain and reconnected the disposal and dishwasher, I've noticed that water from the dishwasher draining will back up and come out of the sink drain. It's not much, maybe an inch. Also, the dishwasher has a funky smell, and after the water has run from the faucet into the sink, I can see that water has filled up the disposal and I have to run the disposal in order to get it to drain.

After looking at my installation, I think I know what I did wrong. Here's a picture I drew because I'm not sure how to explain it.
The first picture shows how my drain trap looks, the second is how I know it should look. Am I right in assuming that the water doesn't drain out by itself because the part after the p trap is higher than the point where the disposal drains out? Would this be why my dishwasher smells funny too, water isn't draining completely out of it?

 

[Dunbar Plumbing]

You hit the nail on the head; the drain in the wall needs to drop in order to resolve the problem. If you are direct connecting the dishwasher to the disposal without a high loop, then this may be the reason for the dishwasher not fully emptying. In KY Air Gaps are mandatory and required by code to prevent the reversal of contaminates of the waste system into a device that produces sterile goods.

The smell you are getting is food waste that is acidic that is souring in the grinding chamber of the disposal; since it is not draining properly this is most likely the cause.


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[Sponsor]

 

[hj]

disposer

You do have a problem and it in turn causes at least two others.
1. The constant water in the disposer will cause premature failure due to corrosion.
2. The water in the disposer will create an unbalanced condition when you turn it on so it will vibrate more than normal for the few seconds it takes to pump the water out.

 

[kanezfan]

OK, good info thanks. I need to get this fixed asap. There's a problem though... I think. The height of the drainage pipe. Where it drains into the wall, it's the same height. I don't know how to make this make sense. The drain pipe, the height that it's at after the P trap, it runs at that same height into the wall and behind the wall and then into a big pipe which runs into the ground. If I changed the part after the P trap to make it lower than the disposal drain, but then had it angle up to meet with the drain pipe that enters the wall, I don't think that resolves the problem, or does it? I really don't want to have to cut the wall open and have to cut the main drain pipe to move the sink drain pipes down, that would be a huge pain in the rear. I've attached another drawing to illustrate what I'm talking about.

 

[Jadnashua]

Nope, it doesn't fix it...you need to break into the wall, cut off the connection from the sink and patch in a section so that it enters lower. From the p-trap, that horizontal run should slope down to the connection of the veritcal drain pipe - ideally 1/4" per foot but never up (otherwise, waste will sit in the pipe and fall back into the trap).Be careful when you cut the pipe...if it isn't supported properly, it could fall and or jam and bind whatever you use to cut it (depends on what kind of pipe).

 

[Cass]

You need to trace back the pipe until you reach the point where the water/drain going horizontal drops verticaly. That point should be a sanitary T. That T is what needs to be lowered to a point that allows it to drain right.