Adding 2nd Bathroom Sink

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by davelzil, Feb 7, 2007.

  1. davelzil

    davelzil New Member

    Feb 7, 2007
    Hi, I want to add a 2nd bathroom sink where now there is only one and read a thread that asked if supplying the 2nd sink from the first one (no new shutoffs) would work or not. Your recommendation was to install new pipes and shutoffs and not tap off the existing sink.

    My question is, how is that accomplished? Is it simply tapping into the copper supply pipes that feeds the existing sink and installing hot and cold and shutoffs or is more extensive piping required? I assume tapping into the existing sink would reduce water pressure if both sinks were running, is that a correct assumption?

    Thanks in advance!
  2. markts30

    markts30 Commercial Plumber

    Sep 25, 2006
    Commercial Plumber
    Phoenix, AZ
    If both were running, the flow to one would be recuced somewhat...
    To tee off for the second sink, you could use a short piece of 3/8" OD copper tubing and compression tees...
    1" piece of tubing into the angle stop with a nut and ferrule then the tee on top of it using another nut and ferrule...
    the faucet supplies then screw onto the other two branches of the tee as they are usually 3/8" compression thread...
    The second sink would need a longer supply line than the existing one...

    Second option, replace the existing angle stop with a double stop (two outlets) and you would have less restriction to flow...
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    If you are going to connect to the existing lines, get a valve with dual outlets, even if it only has one handle. It will be a much better connection than using a tee, unless it is an "Add a Tee" that fastens directly to the existing valve.
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