I have installed a new deeper sink and have found that the wastewater line as currently plumbed it too high for the garbage disposal. It is now a straight line from the disposal drain to the wall fitting.
I would like to lower the pipe coming out of the wall. I have not yet cut the back out of the cabinet, no big deal, it's old. My concern is that the drain line runs horizontal as it is under a kitchen window.
Two questions

1. If the drain line runs vertically can I cut out the T installed too high and place it lower? If so how?
2. If the drain line runs horizontally how does one go about fixing the situation?


Thanks for the info.

Mark

1. It depends on your level of competency.
2. You would have to open the wall to the point where it connects to the vertical line. at that point you would refer to #1 above.

Solid DIY'er. If the wasteline output can be vertically lowered what steps would I need to do after exposing the fitting?
Thanks.

1. Cut the vertical pipe above the existing fitting and again down lower where you want the horizontal line to be.
2. Install new fitting on the lower part of the vertical pipe.
3. cut a short piece of pipe to connect the top part of the new fitting to the upper part of the vertical pipe.
4. Use a slip coupling (one with no internal stop to separate the two halves.
5. Slide the slip coupling up on the top piece of the vertical pipe, put the new short piece in the fitting and align the pipes.
6. Slide the slip coupling down so that it's halfway on both pipes (good idea to mark the pipe first).
7. Cut the old fitting off of the horizontal pipe, use a coupling and the right length of pipe to extend it back to its original length, then re-connect to new fitting in the vertical line.

Process is the same for PVC or copper, PVC gets glued (be sure to prime before gluing) and copper gets soldered. If old galvanized you can use PVC for the new fitting and filler pieces and connect with the proper Fernco fittings.

BUT wouldn't you just use a trap to connect the disposal to the waste line? I wouldn't think the disposal would be after the trap...

Re-Modeling homes for 35 years.
I am NOT a licensed plumber.



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My understanding is that if there is not slight slope to the drain line that the disposal would always have standing water in it and lead to rusting. The drain outlet on the disposer sits at the same level as the drain coming out of the wall. I'm under the impression that the main drain line must be lower for the p-trap to work properly.
Thanks for the assist.



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Instead of a straight piece of tubular plastic, you should use a disposal arm and a p-trap. The height of the wall outlet should be determined by that height requirement. If need be, the outlet can be lower and an extension added to the waste arm of the disposal.

It had a separate p-trap from the sink side. Now that I'm thinking of it, does the outlet side of the p trap have to be lower than the input?
Thanks.

Mark

Why can't you run the disposal line into the sink drain like this?





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This looks good and I'll do that. However, at this time the drain coming out of the wall is just below the drain fixture in the sink. The output of the disposal is at the same level as the drain coming out of the wall. I'm afraid that the waste fixture in the wall needs to be lowered in order to prevent water standing in the disposal.

Mark