Need to move toilet drain pipe but I have questions

Discussion in 'Toilet Forum discussions' started by slamdunk, Jul 2, 2020.

  1. slamdunk

    slamdunk New Member

    Jul 1, 2020
    Raleigh, NC
    Hello All,

    I am in the planning stages of updating a 5' x 5' bathroom built in 1930. One issue I'm studying is the toilet sewer pipe.
    Presently, the toilet has a 16 inch rough in. A wall tank is connected to the pot with a 2" chrome L. I want to make it a 12 inch rough in and it seems easy enough if I cut the 4" cast pipe in the right place, use a 45 , i can swing the pipe to the other side of the floor joist plus a couple more inches. The toilet, tub and bathroom sink are the only fixtures on this 4" pipe that runs about 20 ft before going below ground.

    My three questions are:
    1) The current set up has a wye with a clean out. Do I need to install a clean out?

    2) Would it be bad not to? If I do, the 45 will angle the clean out deeper into crawl space. so a person would have to climb into the crawl space to run a snake thru. I'm thinking it is better to have and never use than not have and someday need.

    3) With modern toilets, would it be better to reduce the sewer pipe to 3" near the toilet or leave 4" all the way to the toilet?

    I would appreciate all feed back. Thanks!
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    Modern toilets work well with 3" pipe. I bump up to 4" when I add the forth toilet.
    Code requires and end of the line cleanout. Often times whoever snakes the line winds up pulling the toilet and snaking from there.
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  4. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    Another option is to use a 3x4 closet elbow/bend. This lets you use an inside or outside 4 inch closet flange even though the run is mostly 3 inch.

    The closet flange could be a compression type that does not get glued. This could be useful for somebody not used to gluing and getting it right the first time.
  5. slamdunk

    slamdunk New Member

    Jul 1, 2020
    Raleigh, NC
    Thanks! I figured pulling toilet on a 4 inch flange would be easier to remove a clog. From flange to run it is only about 15 inches. But if the code requires a clean out, then there will be a clean out. I guess I'll leave 4" all the way. I didn't want to run into a performance issue. Thank you!
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