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Discuss OK for waste to run uphill a short distance? in the Plumbing Forum area at

  1. trf0412

    trf0412 Member

    Currently in the middle of a bathroom refit. Just had first-fix plumbing done and new flooring installed and plumber has sent me some photos of the pipework before flooring went down (see attached).

    The shower and sink waste combine into one before crossing the joists to get to the soil pipe. From the photo the plumber sent me, it looks like there must be a fall from the shower waste down to the sink waste (it's pieces of rigid pipework joined with a straight connector, so can't possibly be falling from both ends, right?). Also, I'm not sure why a T-piece that should be used vertically has been used horizontally? Anyway, my logical conclusion is that water will be permanently sat in the section of pipe between the T-piece and where it turns to go up to the sink. So, if I'm right, that leads to a few questions:
    • Is this going to pose a major problem or will the waste coming from the sink just displace the water in the pipe as it would be coming from a higher source?
    • Will this set-up result in the sink draining too slowly and backing up?
    • Is there a risk the sink waste could get into the shower tray (esp. with the strange T-piece that's been used, meaning the water will need to do a sharp left-turn)?
    • How about the water coming from the shower while showering? Will it all flow via the T-piece down to the soil pipe, or is there a chance it will push water back up the sink waste?

    WhatsApp Image 2017-09-01 at 08.48.27.jpeg

    WhatsApp Image 2017-09-01 at 08.48.16.jpeg
    • Funny Funny x 1
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Needs a fall on the basin pipe and that plumbing also isn't upto par

    • Like Like x 1
  3. trf0412

    trf0412 Member

    Can you give me more details about why it isn't up to par? I'm aware that plumber has drilled holes through joists higher than they should be, but would be interested to know what else you've spotted.
  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Notching and holes arnt really correctly done

    Mix and match push fit fittings

    Inserts in plastic pipe ?

    Long left runs arnt clipped so possibility of a thud every time you close a tap if on mains pressure
    • Like Like x 1
  5. trf0412

    trf0412 Member

    By the way, my questions 1 and 4 had two parts, so I don't know which part your "yes" answers relate to. Depending on which part of the question you were replying to, the answers are complete opposites of each other...
  6. trf0412

    trf0412 Member

    Yes, the notching and holes are a bit of a mess... not really anything I can do about these now, apart from hope they don't cause an issue. The bits of reinforcing wood are only there because I insisted on having them, but I don't know exactly how much they will help things. (A lot of the notches are pre-existing ones, though, so not all done by our plumber).

    The mix-and-match fittings are probably due to the fact that we had a new boiler installed recently and the plumbers on that job used Hep20 pipe and fittings. Our current plumber uses Speedfit and has just continued on from the exisiting pipes/fittings, so I'm not too worried about this.

    Not sure what you mean by inserts in plastic pipe?

    Hmm... thud when turning off tap doesn't sound ideal... we have high pressure mains...
  7. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    First part will cause problems later on if it's falling the wrong way (blocking etc)
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!


    That's fair enough thought he did the lot

    And plastic pipe require inserts internally to the pip

    Pic in attachment

  9. 1Steven

    1Steven Plumber GSR

    I never connect basin with shower.
    • Agree Agree x 3
  10. oz-plumber

    oz-plumber Plumber

    I've seen it all now.

    There is no way that the person who did the waste / drain pipe has any knowledge about plumbing.
    There is no way that will work correctly and will cause you insurmountable problems in the future.

    The way the junction is installed you cannot get fall from the shower or the basin.

    • Agree Agree x 1
  11. trf0412

    trf0412 Member

    Not something I can see, obviously, but I guess he used these. If they are a key element of the join, then presumably there would be leaks without them, right?
  12. trf0412

    trf0412 Member

    What makes you say we can't get a fall from the shower either? (I'm not saying you're wrong, I just have no plumbing experience/knowledge). Is it because half the water will travel down through the sink waste pipe and not all be diverted down the main waste? Would the water not fill up the pipe leading to the sink first and then, once it's full of water with nowhere to go, take the path of least resistence down to the soil pipe?
  13. Stigster

    Stigster Plumber

    Even six inches more waste pipe and an elbow would have improved that situation. Water flows downhill under gravity. Simple as that. Water will drain away from that system but it is going to block at the elbow from the basin because it's a low point/no fall. Soap, hair, oils will gather there.
    Last edited: Sep 1, 2017
  14. snowhead

    snowhead Well-Known Member

    That waste junction wants cutting out now and redoing.

    It would have cost 1 more 32mm Elbow and for the Tee to be in the correct orientation.
    Whoever did that doesn't understand how water flows and wouldn't have been aware of these either;

    POLYPIPE Solv 40 White Cross Tee .. WS38 | Priority Plumbing
    • Like Like x 1
  15. Best

    Best Trusted Plumber

    In short, - he isn't a plumber.
    Amazed that the "plumber" actually took those photos of that work he did and sent them to you!
    Bit like a burglar taking a selfie when stealing your property and then sending you the photo. :)
    Usually work like that is photographed by the customer to have proof or make complaint to the installer. (Or some of us take photos for hall of shame plumbing work)
    I wouldn't want the other work to be completed with same person.
    • Agree Agree x 3
    • Like Like x 1
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