Pro Handyman Blog

P-Trap Plumbing Leak

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One of the first places I look when you have a plumbing leak under a sink is at the P-trap. This is the “P” or “U” shaped drain pipe under a sink. The trap inlet receives water vertically from the sink drain and moves it horizontally out the wall to the house’s drain system. Modern homes use plastic traps, and they get bumped by people moving things in and out of the cabinet.

It is usually not the case that the trap is cracked, although that can happen, rather that the connection between the trap and the other piping is at fault. Run the water and keep an eye out for the leak.

When you find a leak at the connection, you may be able to simply tighten it, or you may want to disassemble it and investigate the source of the leak. Unscrew the slip nut and check that it isn’t cross-threaded. Also, check the slip washer for a crack. If it is cracked it will allow water to pass and drip out of the top of the slip nut. A crack in the washer is hard to see so run your fingernail across it and listen for a “click” sound.

These parts are cheap to replace and take only a few minutes to assemble. Just make sure you seat the washer correctly and don’t cross-thread the nut.