Testing the overflow on your bathroom tub. A four year old saves the day!

Discussion in 'Shower & Bathtub Forum & Blog' started by johnfrwhipple, Nov 26, 2010.

  1. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,449
    Location:
    North Vancouver, BC
    We where saved some massive water spillage last night when my four year old jumped out of the tub and ran to the top of the stairs and screamed "Mommy the tub is really full!!!"

    My wife and I ran up stairs and shut the water off just in time. About a quarter inch more and the tub would have been spilling over the edge...

    What happened? What went wrong with the overflow backup???

    I tested this overflow at rough in stage and it worked? Could one of my kids toys got inside and is restriciting the flow rate?

    I wonder as well if because I tested the overflow with the tub filler off we got a different result as the water was no rushing in at full steam. I feel like the problem is I just bought a "Cheap" over flow and the flow rate is less than the feed rate. Add in the tub filler dropping water and air in the same location and we slowly fill faster than we slowly drain...

    Not good.... What a mess this could have made! My four year old is a "rock star"

    I took great care designing this bathroom and when I did I had never seen a channel drain installed tight to a tub. Had we had this extra channel drain or any drain for that matter in this upstairs bathroom this would have not been so scary. Yet another reason (First Hand) to promote this European backup and yet another reason to buy a channel drain for your next bathroom project.

    I'll get my plumber back to inspect this overflow... I suspect some kind of "Poly Pocket Jumper" to be the route of the problem.

    When was the last time you checked your overflow???

    JW
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,136
    Location:
    Bothell, Washington
    I doubt that any tub overflow will keep up with a free flowing tub spout.
    Normally there is just a small slot that allows water out.
    The overflow will give you "some" cushion for error though.

    When I get calls for leaks under tubs, it's sometimes the rubber seal between the tub and the overflow. I ask, who used the tub last when you saw the leak?
    It tends to be either kids filling the tub all the way up, which would be fine, if the rubber seal was in place and working.
  3. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,449
    Location:
    North Vancouver, BC
    I ran the tub through a worst case scenerio yesterday and noticed the tub like the other night almost overflowed but after the overflow was covered with a 1/2" of water something triggered and the water started to rush down.

    I wonder if there is some kind of rubber damper or such in the overflow that is not working right or has meet with a "Barbie Shoe" or such.

    I called my plumber and hope he can come out an inspect this for me next week.

    Are there any overflows that you can recommend that have a higher flow rate than the rest? Seems to me that this feature should be required to prevent this kind of disaster...

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    Last edited: Nov 27, 2010
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
    Cave Creek, Arizona
    There is NOTHING in the overflow to regulate the water flow. One possibility, since the "slot" is on the bottom, is that if the water was able to rise above it, before the air trapped above the trap could escape, then it would become "air bound" just like a lavatory without an overflow, and then the water would drain very slowly until something happened to let the air "bubble" out, at which time full flow would begin. If you want to test it either drill a small air vent hole in the top of the overflow plate, or invert it and see what happens.
  5. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
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    Location:
    North Vancouver, BC
    Thank You!

    I was wondering if I drilled a hole if this would help.

    I also noticed that the because we "Cheated" the tub filler slightly off center if this in some way was causing issues.

    I will first check that there is no toys inside this overflow and will drill an extra hole or replace with another design.

    I have noticed when I get in that the the water rises (no fat jokes please!) and that it seems to take a second or two before the water starts down the overflow. I feel strongly that it has to be some kind of flapper or washer not preforming properly.

    I would hate for my kids to mess about and cause some huge damage one day. The overflow is a $30 part and I wish I understood this risk better when I spec'd the shower package.

    JW

  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,843
    Location:
    Cave Creek, Arizona
    quote; have noticed when I get in that the the water rises (no fat jokes please!) and that it seems to take a second or two before the water starts down the overflow. I feel strongly that it has to be some kind of flapper or washer not preforming properly.

    There is NOTHING to perform properly, but you have proved my suspicion. When you get into the tub, it raises the water level TOO quickly for the air to escape before the slot is submerged. A hole anywhere would let the air escape before it got covered up, but, since it would be on a vertical surface, the air would still "bubble out" even if it were to be submerged.
  7. Try twisting the overflow plate so the slot is not flat on the bottom to help start letting trapped air out on the upper edge.
  8. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    I decided long ago that tub overflows that we see today are ridiculous
    and cannot possibly work on two open faucets. They should look like a shower drain.

    But I always turn them slot side UP to give more water level, and now appreciate their mis-design.

    My kid once tested the sink overflow by plugging the drain and leaving both handles full on until it started to rain in the room below.
  9. floor drains in bathrooms are the answer. Channel drains (better) or old fashioned drains that require a cone shaped slope in the floor.

    This is what got to come to this site, years ago.
  10. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,449
    Location:
    North Vancouver, BC
    Emergency floor drain...

    There is no way to add in a nice channel in front of my tub but I could cut in for a regular floor drain under my vanity. We graded the entire floor so water would not sit against any wall or tub and I think If I place a new drain in this spot the drain would come into action in a worst case scenerio. The ceiling below the vanity is in a closet and or my wife's pantry so it should be easy to get to...

    Before going this route I will follow the advice above and see what improved results I get.

    Thanks men.

    JW
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