I am in the process of a kitchen remodel and now have come to the plumbing. My original kitchen had a 2-bowl sink and my new kitchen will have a 30" wide sink base with a 27" wide single bowl. There also will be a garbage disposal with the new single bowl.

It is my intention to remove all the in-wall copper pipe and replace it with ABS, and somewhere in my basement I'll switch from ABS back to the original copper with a fernco coupling. In the wall will be a simple tee that will give me a through-wall flange for the outlet of my garbage disposal.

My question is, how high off the floor should I make my drain? I'm thinking the lower the better, that gives me more clearance for my garbage disposal, however it needs to at least be high enough that the trap is still above the floor of the base cabinet. I have no dimensions of the base cabinet, but I'm guessing the floor above the toe-kick is ~4", and I'd need another 8" for the trap to clear, so I was guessing around 12"?

My only research brought me here, however it makes no mention of the garbage disposal and how to plan for that.

Existing plumbing with proposed overlayed

2 Answers 2


12 inches above the floor is really cutting it close. Most cabinets have a kick toe of 6 inches so you'd only have 6 inches to install and work the trap. I'd be looking at 16 to 18 inches above the floor. Good luck.

  • Does the height of the garbage disposal not matter then? I guess that's why most have side exits?
    – DrTarr
    Aug 15, 2019 at 15:48
  • They have side exits and come with a ABS down pipe that's 5 inches for adjustments and there are extensions for the trap so the height of the disposal is not a problem.
    – JACK
    Aug 15, 2019 at 16:07

You are going to have a disposer in a single basin sink? I would never disturb all that original copper drain pipe for such a project.

Rethink this.

Disposers are not even allowed in new construction in some jurisdictions. They waste water and unnecessarily add food waste to the sewage stream. Food waste should go in the garbage.

  • Regarding the ethics of a disposal, I think that's up to me. Could you elaborate why you wouldn't disturb the copper piping for a single bowl sink?
    – DrTarr
    Aug 15, 2019 at 22:30
  • It is not just social responsibility to forgo a disposer. They are troublesome and noisy. If you have to put in drain cleaner to clear the trap, you have to put it through the disposer. If you have a single basin sink with a disposer, you cannot run one of those small snakes through to clear the trap. But you are right: I am opposed to the installation of disposers and so the negative aspects of a disposer are not balanced in my mind by any benefits. Aug 15, 2019 at 22:37
  • Could you install the sink you have selected with the trap on the existing drain (as shown in the picture) or is the stub out drain too high? Aug 15, 2019 at 22:42
  • I believe this is outdated. They were sometimes banned in the past, but these bans have mostly been lifted after many studies have shown them to be OK, especially the more modern ones. But people should be careful what they put down them, more for their own sake. Oct 4, 2021 at 0:11

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