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Waste pipe flowing wrong direction?

Discussion in 'Plumbing and Central Heating' started by Lauraheard12345, 27 May 2021.

  1. Lauraheard12345

    Lauraheard12345

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    Hi guys,
    So I’m desperately after some advice! Since moving into our house a few years ago the sewer pipes always get blocked. We’ve had professionals clean them but they still clog up after a few months. What I believe to be happening is my waste pipes are not on a steep enough gradient and/or slightly going the wrong direction and then waste is getting backed up (ewwwww!) I just emptied the bath and checked a drain that is in the wrong direction and there was a steady flow I have no idea how to measure the gradients as all the online advice seems confusing!
    Any suggestions on help or advice is gratefully received, it’s such a Grose problem to have! Thanks in advance.
     
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  3. Harry Bloomfield

    Harry Bloomfield

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    They cannot be sloping in the wrong direction, or there would be no flow. If you can access the bottom of the sewer in two places, you can check the fall with a couple of lengths of timber, a water level and a tape measure. Just drop the lengths of timber own the holes to the bottom of the pipes, then use the level to put pencil marks at the same level on the two timbers. The difference between the marks, is the fall.

    Are you sure your pipes are not collapsing, or choked with tree roots causing the problems?
     
    Last edited: 28 May 2021
  4. Lauraheard12345

    Lauraheard12345

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    Thank you Harry. We had a camera survey done recently and they didn’t pick up any collapsing of pipes etc... I did find a bit of old rust in the drain recently though, could this be a sign of a collapsed old pipe? The property is 1940’s so the drains are old. The pipe ends at my house and then goes into the front and into the main sewer so my concern is that the water is flowing to the dead end and not the main sewer. Thanks for your help
     
  5. Harry Bloomfield

    Harry Bloomfield

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    If the pipe is empty, until you flush the toilet or empty the sink and when you do you almost instantly see that water flow past - then the drain is working properly.
     
  6. Hugh Jaleak

    Hugh Jaleak

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    CCTV Survey should have picked up any 'Belly' (dip) in the pipework, otherwise apart from seeing the flow of water in the bottom of the pipe it isn't always easy to tell what sort of fall, (if any) is on a drain. Theoretically you could measure the invert depths and calculate the gradient between the 2 points, but that isn't a hard and fast rule, pipework could still be wonky in between.

    Did the CCTV throw up any other issues? Bad joints, root ingress, damaged or collapsed pipework? Lastly, are you (or anyone else in the property) in the habit of putting wipes, sanitary products etc, or any large amount of fat down the drain?
     
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  7. Lauraheard12345

    Lauraheard12345

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    The cctv said there was a raised bit slightly but said it shouldn’t be an issue. We never put anything down the drain (not even toilet tissue anymore) as we want to leave it as clear as possible.
     
  8. Hugh Jaleak

    Hugh Jaleak

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    If you do have a 'Backfall' (i.e. drain is sloping uphill), there is no solution other than to dig it up and relay it to the correct fall I'm afraid.
     
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  10. CBW

    CBW

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    But Harry said they can’t slope (sorry, slop using his words) the wrong way :LOL:

    OP - is it just the drains then I take it, or is the soil pipe affected?
     
  11. Lauraheard12345

    Lauraheard12345

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    I’ve attached a drawing of the drains. It’s by no means technical but might make it a little clearer. Thanks everyone
     

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  12. Lauraheard12345

    Lauraheard12345

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    Attached diagram
     

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  13. Hugh Jaleak

    Hugh Jaleak

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    Afraid all that tells us is what the layout looks like and which way they run. Sometimes pretty obvious if your on site, looking at things whether there's a backfall or not, and a CCTV survey will soon show any low points in the system as they'll remain full of water.

    A CCTV survey is probably the next best course of action, (you may find it cheaper using a local Independent, but get a written quote first, (sadly there are still too many Cowboys and Con Merchants in the drainage game.) See what, (if anything) that throws up, and come back to us for further guidance, (do not be suckered into expensive remedial work that may not even need doing.)
     
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  14. Lauraheard12345

    Lauraheard12345

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    Thank you for your help. I’ll ask someone to come out again
     
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  15. Nige F

    Nige F

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    Your diagrams are OK but if we had some measurements between the manholes we could possibly suggest an above ground soil/vent pipe layout. Also a picture of the wall with the manholes in the ground too ?
     
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