The plumber just finished my kitchen sink installation, and I noticed that the horizontal pipe connecting the two sink bowl drains has a slight up-slope (maybe 1/8") over its length toward the point it "T"s into the trap. As I see it, there will always be a small amount of water puddled in the pipe because of this. To do it right, it should be sloped toward the trap. My question is: is this really a problem waiting to happen? Do I need to call him back to re-do the drain? Or am I just overly fussy?

  • there is always a not so small amount of water in the trap. I agree with Michael just adjust the slip joint on the tail piece up.
    – Alaska Man
    Commented Mar 19, 2017 at 12:54

1 Answer 1


I do not think you are overly fussy if you paid someone to install a drain line it should be done correctly. That said a drain to drain connector that was just a 1/8" difference would allow such a small amount of water to puddle in the pipe that it would evaporate in short order anyway.

Most of the piping pieces to make up a drain and trap assembly are typically joined with slip joints that can be easily adjusted. You may be able to simply move one or two joints slightly to correct the slope and avoid the aggravation of trying to re-engage with the plumber.

  • I didn't think there would be enough flex in the (black ABS) pipe to make such an adjustment - that the slope is pretty much committed by the way the pipe was cemented in to the T joint for not more than about 15" of pipe.
    – Anthony X
    Commented Mar 19, 2017 at 14:42
  • If the whole drain pipe is composed of cemented together ABS or PVC pipe there is little chance of doing any adjustment. I was referring specifically to the types of drain components that are made up of slip joint connections.
    – Michael Karas
    Commented Mar 19, 2017 at 15:37
  • The sink drains have brass tailpieces; the ABS connects to the tailpiece via a union (I assume it's what you are calling a slip joint). However, from that point downstream to the trap, it's all cemented joints. The trap incorporates threaded joints, but won't really accommodate adjustment in the direction it needs to go. Yeah, maybe I can loosen the trap and one of the tailpiece connectors to make an adjustment, and hopefully it will stay that way when tightened back up.
    – Anthony X
    Commented Mar 19, 2017 at 16:26
  • Hopefully it will work out to adjust. Good Luck.
    – Michael Karas
    Commented Mar 19, 2017 at 16:37

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