Dual ptrap dilemna

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Spirock, Jan 17, 2009.

  1. Spirock

    Spirock New Member

    Jan 17, 2009
    I am remodeling my laundry room and would like to add a sink next to the washing machine.

    The drain is in the wall in the cement floor. At floor level, a cleanout comes just outside the wall. Then a very short pipe comes out just above the cleanout and it has a ptrap attached which then extends upwards about 24 inches and the washing machine drains into it.

    I want to put a cabinet and sink in that corner and move the washing machine to the right of the cabinet. I understand once the new sink is in, I can just drain the washing machine into an inlet just above the new sink ptrap.

    My problem is that there is not even a sliver of pipe available where the old ptrap is to allow me to cut the old ptrap out and create just a drain pipe going to the new sink.

    My question is, can I just leave the old ptrap in, and cut into the old washing machine drain pipe to create a drain for the sink and the moved washing machine?That would mean I have two ptraps now, the old one near the floor, and the new one below the sink in the cabinet with the washing machine connected to drain just above the new sink ptrap.

    The two ptraps would be about 24 inches from each other.

  2. Basement_Lurker

    Basement_Lurker One who lurks

    Jun 21, 2007
    I smash things and demand money.
    Victoria, BC
    No you can't do that. Double trapping your trap arm is very naughty.

    All new washer installations must be done with a 2" line with a 2" p-trap, so even if your local code allowed you to combine the standpipe with an existing sink fixture outlet pipe, you would still have to break open the wall and upgrade that trap arm to 2".

    Since you are renovating anyways, just bite the bullet and break open the wall and run separate trap arms to both fixtures properly and be done with it.
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  4. Spirock

    Spirock New Member

    Jan 17, 2009
    one ptrap for both sink and washing machine

    The new sink would be right beside the washing machine drain stack.Can I not let the sink drain just above the ptrap of the washing machine stack and then still put the washing machine hose back into the top of the drain stack for draining of the washing machine?

    The new sink drain is less than a foot sideways to that trap. This way I would be using the washing machine trap for both with adding a T only.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    You would not have a "double trap" in the ordinary use of the term. Yours would drain, while a true double trap would not. But there are ways to cut the trap off and bore the piece of pipe out of the tee so you could insert a new piece. Either way would work.
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