In a utility sink in my basement, I’ve always had problems with the sink leaking when there is water to drain. It’s never been a huge problem because the sink wasn’t used often so I didn’t mind if the drain dripped a little. For various reasons, now we want to fix this and I’m not having much luck.

Is my sink too low to get a proper drain? I can raise the sink if needed but would rather not if I can avoid it.

I am not 100% certain, but I believe the source of the leak is through the threads just above the P trap. I’m assuming this connection isn’t made to seal off liquid from essentially rising from below.

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  • Where is your drain vent ?
    – Traveler
    Mar 6, 2023 at 21:55
  • 1
    Right behind the drywall
    – Richard
    Mar 6, 2023 at 23:15
  • One hint to help you make sure the vertical extension is aligned with the drain fitting is to loosen the compression nut where the drain extension enters the P trap and then loosen the compression nut where the 90 degree fitting slides into the drain. Hand tighten the nut on the vertical drain extension first. This will align it properly as the horizontal section will have some play in it. Tighten the nut on the horizontal section last.
    – HoneyDo
    Mar 7, 2023 at 3:12
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    Make sure your compression rings are facing the right direction...
    – Huesmann
    Mar 7, 2023 at 13:08
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    – isherwood
    Mar 30, 2023 at 20:44

2 Answers 2


The sink is not too low

Everything appears to slope the proper direction.

Looks like the trap is cocked (at an angle to) the tailpiece entering it, which probably has something to do with the leak there.

Get it straight (loosen the slip joints and the mid-trap joint - rotate, slide and twist as needed) and it should seal better. Perhaps get a new sealing washer for the slip joint, but start with getting it lined up straight. Then tighten all the joints. It should, in fact, seal there.

  • I do think it’s straight and may be lighting/shadows. BUT! I will double check that when I’m checking the rest of the stuff, thank you!
    – Richard
    Mar 6, 2023 at 23:31

If the drain and/or P-trap is leaking replace the seals or replace the whole drain/p-trap assembly. The height of the sink is not the problem. There is no minimal distance between sink and P-trap, but there is actually maximum permissible distance (e.g. 24in in Florida)

  • Thanks. I thought that if the sink was raised then the threaded connection right before the trap would be high enough so that the water couldn’t rise from below, but if I can get that connection water tight then I will try to replace and make sure I seal well. Thanks.
    – Richard
    Mar 6, 2023 at 21:12
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    This answer strikes me as overkill. I've never seen worn out plastic compression fitting seals. It might just need a little tightening.
    – isherwood
    Mar 6, 2023 at 21:25
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    tighten the connections. i've certainly had to use tools to tighten the connection on abs trap pieces before to get them to seal. you just don't want to crack them so go easy - worse case you are in the same boat as above - replacing pieces. Mar 6, 2023 at 21:27
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    @isherwood just went through replacing bathroom drains that were corroded and seals crumble in hands Mar 6, 2023 at 21:41
  • If the drain has been over tightened at some point that could damage the seal rings.
    – FreeMan
    Mar 31, 2023 at 13:21

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