+ Reply to Thread
Results 1 to 7 of 7

Hybrid View

  1. #1
    Join Date
    Aug 2012
    Posts
    4

    Default Problem w lower toilet

    The lower of the two toilets in our 2-story house occasionally overflows. It has happened only a few times, most recently (twice) when the upper one is flushed. The lower toilet feeds into a 3" ABS drain about 6' from the house, where the drain runs to the septic tank. The drain was installed with a 1/4" per inch slope; the two drains are connected with a standard "Y" fitting. After one of these episodes, the lower toilet flushes normally - no plunger needed. I dumped five gallons of water down, no problem.
    Background: research tells me that each flush does not necessarily deliver all solids all the way to the sewer/septic tank; small, temporary "dams" occur, and the system depends not only on flushes, but also on waste-water from sinks, tub/shower, dishwasher, etc., to move solids and keep the drain clear.
    IF this is correct, I believe the most recent incidents occurred because these small "dams" had a chance to dry a bit -only one person was in the house for a week or so each time, so less waste-water was used, maybe not enough to clear the line frequently.

    The question is how best to deal with this. I'm considering moving the "y" so that the drain from the lower toilet joins the other 3" line as close as possible to the septic tank. Advice/questions/comments/suggestions welcome!

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,093

    Default Re: Problem w lower toilet

    It would be a good idea to have 4" line past the Y.

    You may have a partial block past the Y. If you have a clean out at this point, try to run a snake and see if it drains normally.

  3. #3
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: Problem w lower toilet

    Is the Y vertical (in the wall or in the crawl space)? Where the lines reach the main drain line, does the fitting have a curve so that it enters the main line at a 45 angle and is it pointed toward the septic tank?

    I fully agree with dj1 that the output of the Y should be 4", especially if vertical. also, are these 1.6 gal per flush toilets?

  4. #4
    Join Date
    Aug 2012
    Posts
    4

    Default Re: Problem w lower toilet

    The wye that joins the lines is horizontal, underground about 6'from the house. Toilets are 1.6 gpf. I agree 4" line after the wye would be a good idea. I've tried flushing both toilets at the same time, and can't get the lower one to back up. What's peculiar is that the lower toilet floods only rarely, and unpredictably. Most recently it has been when only one person was there, house-sitting for a week or ten days. That's what makes me think it's a problem of gradual build-up in the 3" line. Before I added the lower bathroom, the height (10') of the upper toilet probably provided enough force to keep the horizontal line clear.
    Thanks for the feedback.
    Two other possible solutions : 1) replace 3" horizontal lines with 4" and 2) increase slope of both lines from 1/4"/ft to 3/8" or 1/2"/ft., if position of septic tank will allow it. What do you think? I have plumbed houses and installed septic systems successfully, but I'm not an expert. Never encountered this particular problem before!

  5. #5
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,093

    Default Re: Problem w lower toilet

    Replace the 3" line with a 4" line, including the Y.
    Snake your drain from the two toilets all the way to the septic tank (if need, remove the toilets to gain access).
    See if this helps.

  6. #6
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: Problem w lower toilet

    The simple solution might be when only one person is in the house for an extended stay, they flush twice and take their time washing their hands after each solids flush. That won't be a significant amount of water usage.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •