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Thread: Kitchen sink backing up when washing machine drains

  1. #1
    DIY Junior Member Petra's Avatar
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    Question Kitchen sink backing up when washing machine drains

    Hi, we live in a no-basement rancher which was built in 1982, on a concrete slab foundation. We bought this house 2 1/2 years ago, and the septic tank was emptied at that time.

    For several days last week, every time the washing machine, which is hooked up in the garage next to the kitchen, was in use and draining water, the water backed up into the double sink in the kitchen and overflowed. The water contained lots of debris. We also have 2 bathrooms, and luckily nothing backed up in there, knock wood. Also, nothing backed up when I used the dishwasher in the kitchen. The plumbing is pretty old, most of it probably original and, as far as we know, it was installed in the foundation.

    We called a plumber who was here for 2 hours, cleaning out the drains with some type of machine. They went up to 68 feet and had to run it through several times until it started clearing. It was still not draining 100%, so the plumber advised us to buy a cleaner called "Thrift". He said it is safe for septics. After we applied Thrift, everything was back to normal and no sink backups when using the washing machine.

    But earlier today I washed another load of clothes on the low cycle, and though no water backed out of the washing machine drain, the sink gurgled and a little bit of water backed up. This water was clean, no debris like before. The water drained immediately, but we are concerned that this problem has not been completely solved. Any advice would be much appreciated.

  2. #2
    In the Trades Gary Swart's Avatar
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    Default Backup

    It sounds like your drain is still partly clogged. A washer puts a great deal of water into the drain and a partly clogged drain just can't handle that much all at once. Every "real" plumber that subscribes to this forum condemns chemical drain openers. I'd suggest you try a different plumber. Make sure you contact someone who is in the plumbing business, not just a sewer service. Often these people do not have extensive plumbing training. All they can do is run the auger. That may be enough in most cases, but when there is a problem beyond a blockage, they run out of know-how.

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    DIY Junior Member Petra's Avatar
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    Default

    Hi, thanks for the reply. The plumber we called has been in business for quite a few years. We did get the impression he didn't really know what to do when the washing machine still backed up after they ran the line (auger?) many times. We are going to call a different plumber if the sink continues backing up. Any advice on what the next plumber should do once we explain that the previous plumber ran the machine and things are still not clear? We are out over $100 already and don't want to have to pay for another useless service call. Also, I gather from your reply that it was not a good idea to use this Thrift stuff, should we expect any damage or problems due to using it? And one last question, the plumber recommended that we regularly pour enzyme cleaner down the pipes, which he explained acts like pac man and gobbles up grease and other organic waste, are those cleaners effective?

    Many thanks,

    Petra
    Last edited by Petra; 11-21-2004 at 11:58 AM.

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    DIY Junior Member carol's Avatar
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    Default

    I have a similar problem, although now just the toilets gurgle and nothing overflows. I am interested in any replies you get on this subject.

    Someone in another thread suggested clogged plumbing venting. Last year, when back pressure from the draining clothes washer caused a pipe under the kitchen sink to blow off, the plumber got on the roof and snaked down this vent.

    I would also like to know what we are supposed to do about today's washers that have no lint screens (thus causing huge problems for us septic owners). I do not have room in my laundry room to install a deep sink and use those mesh lint screens. I have used them in my deepsink in our previous home, and as many times as those mesh lint bags (that attatch to the drain tube of a washer) blew off into the deep sink, I won't even entertain the idea of tempting fate by using them in a regular pipe (to blow off and clog the thing).

    Carol

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    Forum Admin, Expert Plumber Terry's Avatar
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    Default rough-in for laundry tray and washer standpipe.


    I would check to see if the washer p-trap is vented.
    The picture above is a rough-in for a laundry sink and a washer standpipe.
    Without the venting, you can easily back up other fixtures like a kitchen sink.
    Been there, done that.

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    DIY Member yngwie_69's Avatar
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    Default I dont get the stand pipe vent

    Quote Originally Posted by Terry View Post

    I would check to see if the washer p-trap is vented.
    The picture above is a rough-in for a laundry sink and a washer standpipe.
    Without the venting, you can easily back up other fixtures like a kitchen sink.
    Been there, done that.
    Why does the stand pipe need its own vent. cant it share the same vent as the sink.

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    Forum Admin, Expert Plumber Terry's Avatar
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    In the UPC code, they don't allow a laundry tray to wet vent over a washer.

    They only allow wet venting on bathroom fixtures. Which a laundry tray is not.

    In Canada and Phoenix they may think differently.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Default

    WIth the internal pump, the WM can move a LOT of water quickly...it just makes sense that it needs a proper vent to keep from either pressurizing the line or creating enough velocity to suck some other unvented trap dry. It also requires the drain line to be big enough (and in the USA, that's been determined to be a 2" line).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member yngwie_69's Avatar
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    Default

    Quote Originally Posted by Terry View Post
    In the UPC code, they don't allow a laundry tray to wet vent over a washer.

    They only allow wet venting on bathroom fixtures. Which a laundry tray is not.

    In Canada and Phoenix they may think differently.
    would u recomend this setup even know my code dont require it

  10. #10
    Forum Admin, Expert Plumber Terry's Avatar
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    Default

    The previous drawing you have posted shows many more fixtures.


    A standard laundry trap drain is pretty small.
    Some people are installing kitchen sinks and using them as laundry trays.
    Some are using kitchen sinks as bar sinks.
    Either way, a kitchen sink and it's drain has never been allowed as a wet vented fixture.
    They drain water much faster.
    It's why the code says that wet venting is allowed for "bathroom" fixtures. Not for sinks.
    Last edited by Terry; 05-18-2013 at 11:19 AM.

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