kitchen sink/disposer plumbing

PJain · Posted: Sat Aug 06, 2005 1:49 pm Post Subject: kitchen sink/disposer plumbing

I am replacing my kitchen countertop and want to install an undermount sink which is also deeper than the current one. So I have to lower the garbage disposer. currently there is a s-trap connected to the disposer and the s-trap goes into a horizontal pipe. Can I use an L-shaped pipe between the s-trap and the horizontal pipe to lower the disposer by 3-4 inches? Would you recommend any other maximum height of the L-pipe? Any help would be appreciated. thanks.

Nige F · Posted: Sat Aug 06, 2005 4:22 pm Post Subject:

Here in the UK the only garbage disposers I`ve come across in 35 years are broken ones that we`ve removed

...Not much use for them here.Sorry

ChrisR · Posted: Sat Aug 06, 2005 10:06 pm Post Subject:

EH? Well mine works fine thankyou very much. Sounds like the grot gobbler and the sink each have their own S trap, and then the pipe goes to a horizontal. That's absolutely fine. As long as the pipes which aren't part of the trap itself are all downhill. If you have to go UP with your L shaped pipe to the horizontal one, you'll be making another trap which is, er, not ideal!

PJain · Posted: Sun Aug 07, 2005 2:32 am Post Subject:

Chris, thanks for your reply. I checked again and I was mistaken about the s-trap. Actually the horizontal pipe coming out from the wall has a p-shaped pipe from which another pipe comes and goes up a few inches to connect to the garbage disposer. what do you think is the best way to lower the disposer?

ChrisR · Posted: Sun Aug 07, 2005 7:24 am Post Subject:

It's best if the WD and the sink have their own traps, doesn't matter which type, to reduce the amount of pipe above the water line in the trap(s). This is to reduce the smells which come up.
After the trap you'd just use whatever you need to get to the common exit.

tim00 · Posted: Mon Aug 08, 2005 1:20 pm Post Subject:

PJ, what state are you in? The Uniform Plumbing Code does not allow S-traps. So presuming a P-trap:
when your sink is lowered the garbage disposal will lower by the same amount, hence your trap arm will find its own outlet level.
The trap arm should run into the wall and be picked up by the sanitary tee in the waste and vent pipe.
From your description you will have to open up the wall and cap the old arrangement.
Come back if the above suggestion is not feasible.