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  1. #1
    Join Date
    Apr 2013
    Posts
    2

    Default adding second toilet to 3 inch drain

    I would like to add a second toilet, in a new bathroom, on the back side of our main second floor bathroom. The main bath toilet currently drains into a 3 inch pvc pipe. Can I simply add the second toilet down the line from the main bath toilet? Understanding, of course that the venting would have to be proper. I read somewhere, that, if you are adding a second toilet you have to increase the size of the drain from that toilet on.

  2. #2
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,168

    Default Re: adding second toilet to 3 inch drain

    3" is OK for two toilets.
    John

  3. #3
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,361

    Default Re: adding second toilet to 3 inch drain

    When I was plumbing 15 years ago, you could install up to three toilets on a 3" drain.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  4. #4
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,168

    Default Re: adding second toilet to 3 inch drain

    Quote Originally Posted by Fencepost View Post
    When I was plumbing 15 years ago, you could install up to three toilets on a 3" drain.
    You're correct but before the low flush toilets you were only allowed two toilets on 3".
    Last edited by johnjh2o; 04-17-2013 at 08:06 AM.
    John

  5. #5
    Join Date
    Apr 2013
    Posts
    2

    Default Re: adding second toilet to 3 inch drain

    Does it matter that there will also be a sink, tub and shower on the same line?

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