I have just replaced dual bathroom sinks and installed new P-traps and faucets.
Now I have a smell when using the water in both sinks.
Can the P-traps not be properly leveled or installed?
enter image description here

  • The trap looks good it should hold enough water to prevent any back flow of sewer gas. The question I would ask you said they smell when using water can you explained or give more detail on the smell and any other info.
    – Ed Beal
    Dec 20, 2018 at 14:06
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    Original installation had no smell. It smells like sewer fumes but, not strong. Just around the sink area when leaning down to use faucets. I did replace both faucets as well. Recently install a whole house filter also to reduce iron levels. No other sinks have smell when using them (kitchen, other smaller bathroom at same floor of this install). Since these are new sinks I do not think the overfill is the problem. Dec 20, 2018 at 14:13
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    This is a weird issue. P traps block the sewer gas by filling up with water, it's pretty basic, hard for something to go wrong. maybe something got spilled under the sink during install? Try cleaning everything with a little bleach? Dec 20, 2018 at 16:20
  • Are you sure it's not the water itself, as a result of the new filter?
    – isherwood
    Dec 20, 2018 at 17:04

2 Answers 2


The most likely cause would be syphoning, where the flow of water in the waste pipe empties the P-trap. This could be due to too small a diameter pipe and/or lack of vent in the pipework to prevent a vacuum caused by draining water. Did you change any other pipework apart from the P-traps?


If there's no leakage, something must be wrong with the unions where there's no water stored when water doesn't flow. I don't know what you used to connect the pvc/cpvc/abs pipes.. pvc glue, teflon tape... if everything is ok, and is the same model in both p-trap you should check the model reviews, if not, like one said, the diameter is really important when talking about p-trap (minimum diameter p-trap 1¼"). But with only one photo I can tell you more.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Sep 23, 2019 at 21:01

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