Toilet Supply Hose leaks after showering

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by stotzies, Jun 5, 2008.

  1. stotzies

    stotzies New Member

    Jun 3, 2008
    I replaced a leaking supply tube to my toilet. It stayed dry overnight but 10 minutes after I finished showering water started bubbling out the top of the upper connection. It's possible I damaged the threads and need to replace that part also. But I'm wondering if a draining shower can cause back pressure somehow on the water supply to the toilet? Is that normal or do I have a larger problem?
  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    I can't tell you what the problem is for sure, but I can tell you that the shower drain, or any other drain, and the toilet supply line, or any other fixture supply line, are in no way interconnected and can not possible affect one another. I would suspect the threads on either the supply line or the fill valve were either damaged by over tightening, cross threading, or perhaps are not tight enough.
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  4. JeffH

    JeffH New Member

    May 21, 2006

    That's a tough one, It could have something to due to fluxuation in pressure at that connection. When you run the shower pressure is relieved at the toilet. Some so so connections possibly could be sensitive to it. When you say "supply tube", do you mean copper tube or flexible supply line? If you have an actual copper tube, you might want to try a flexible braided supply hose as a test. Did you reuse a cone washer? Don't, as they conform to what they are sealing and want to stay that way. They don't like to re-conform to new shapes or surfaces.

    Also, drain & supply have nothing to do with each other, other than their obvious functions.
  5. SteveW

    SteveW DIY Senior Member

    Feb 11, 2005
    Omaha, NE
    Here's a new theory:

    Maybe you are having thermal expansion problems!

    That would explain why the leak would start a few minutes after showering - that is, when the water heater would be running to replace the hot water you used.
  6. Redwood

    Redwood Master Plumber

    Dec 15, 2007
    Service Plumber
    As I was scrolling down through the thread I was getting ready to post about Thermal expansion! Nice diagnosis Steve! I believe you nailed it!

    Pick up a water pressure gauge that threads onto a hose bib, and measure your water pressure. Run the cold for a few seconds just prior to taking the reading just in case there is already pressure from thermal expansion. Take a reading and watch it for a couple of minutes. It should remain steady at less than 80 PSI.

    Then have someone take a nice long shower and after the water is shut off go back and watch the pressure climb... Post back with how high it goes!
  7. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Your diagnosis and description are not reasonable. Any plumbing connection can withstand a lot more pressure than thermal expansion creates. Unless you also have an additional problem, such as a dangerous malfunctioning pressure relief valve.
  8. edlentz

    edlentz New Member

    May 26, 2008
    Did anyone mention "Sweating" of the supply line?
  9. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    I believe stevew's diagnosis makes a lot of follows logically from the op's scenario. A marginal gasket or fitting which did not immediately show any signs of leakage at 55 psi could easily fail as the pressure increased to perhaps 150 PSI. We don't know IF this all happened....testing will tell that tale.
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