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Thread: toilet runs

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  1. #1
    Join Date
    Nov 2007

    Default toilet runs

    Hi all. We have a toilet in our master bathroom that runs from time to time when no one is up there. I've been checking for a leak, or listening for water dripping when it's off, but I don't hear or see anything. It's starting to go more often now. What do I look for? What could it be? Is it an easy fix?

  2. #2
    Join Date
    Aug 2008

    Default Re: toilet runs

    This is usually a reasonably easy fix.

    This type of leak could be caused by any one of 3 conditions; the most likely is a worn or caked-up ballcock (refill) valve or a worn diapragm washer inside the ballcock valve that is allowing a slight amount of water to silently bleed down the overflow tube.

    If you're not familiar with the terms mentioned, study the websites below & study your own particular style of toilet tank innards until you understand how the flush/refill/shutoff mechanisms work.

    When you push down on the handle to flush, there is usually a thin chain attached to a flapper valve that is pulled open so all the tank water drains out at once, this flushes the bowl contents down the sewer.

    This also opens a ballcock (refill) or fluidmaster-type valve in the tank so the tank can refill with water again; on older tanks, there's a ball float attached to a metal arm that raises the ballcock valve & shuts off the water supply when the tank is full.

    AS time goes by, (especially if you have hard water with a lot of minerals), some crud gets into the valve shutoff & it no longer closes completely.

    As an initial step, take some WD-40 or other lubricating oil & apply a few drops on the top central portions of the ballcock mechanism (if you have such a setup)---sometimes over the years gunk piles up at this location & allows a slight leak.

    Shut off the water supply to the tank, behind the toilet & flush till the water is gone---then move the metal float arm up & down several times to exercise it & to loosen any internal crud that may be present.
    Last edited by dodsworth; 10-01-2010 at 07:51 AM.

  3. #3
    Join Date
    Aug 2007
    The Great White North

    Default Re: toilet runs

    Also check for a misaligned or worn flapper not making a seal or the fill level may be too high and spilling over into the overflow/fill tube.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  4. #4
    Join Date
    Jun 2007
    Fayette County, Ohio

    Default Re: toilet runs

    The primary cause for this type of situation is a worn flapper valve or dirty flapper seat. It is easy to verify. Dump some food coloring in the tank and let it set. If the water in the bowl changes color the flapper is leaking. Easy DIY repair.
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #5
    Join Date
    Nov 2012

    Default Re: toilet runs

    I had the same problem and determined it was the flapper. Fun thing was both of my bathrooms had the same problem within a week of each other. Has anyone ever heard of a flapper shrinking? I believe that is what happened and was allowing just a bit of water to escape. I replace the flapper on both toilets and fixed the problem. I'm just curious if flapper shrinkage can occur. Hey, that sounded like a line from Seinfeld.

  6. #6
    Join Date
    Jul 2010

    Default Re: toilet runs

    I don't think that flappers actually shrink, but they sure lose elasticity and flexability and thus don't provide a complete seal anymore.

    But sometimes the leak continues even after replacing the flapper. That's the time to look at the flush valve. Replacing that is a bit more invloved.

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