We installed new counters and along with it a new sink. The location of the drain on new sink is lower and much to the left of the old one. After rotating the trap, its still off from the drain by about an 1. But there isn't enough vertical room to make the necessary jogs. So my question is, would it hurt to add a s trap right out of the sink drain only to jog the h2o to the location of the orginal trap? Would it still drain correctly? Would the lower trap still work correctly? See the attached sketch.sketch


  • Are these two sinks right next to each other (like a double basin sink)? – Tester101 Feb 12 '15 at 20:08

I don't believe you're allowed to have two traps on the same drain line at all, and you certainly don't want two in a row. You will surely get weird syphoning and gurgling problems.

Just replumb the new sink so that the drain goes straight down and joins the old sink's drain before the P trap.


If these sinks are close enough to share a trap arm, then I see two options.

Down and over

down and over

Over and down

over and down

You never want to put two traps in a row, and you never want to use an S-trap.


S-traps are not typically allowed. The reason is that an S-trap, by design, tends to siphon the trap. To make an S-trap into a P-trap the horizontal run after the first trap has to be significantly longer.

I'm not a plumber, but I believe because both your sinks drain into the same line that DOES have a P-trap, you might be OK with just the one P-trap (Provided it's all vented properly)

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