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Discuss Grey Water pipe size? in the Fittings & Pipes area at

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  1. Charlie080

    Charlie080 New Member

    Hi all,

    I have a grey water waste pipe which keeps getting blocked. The pipe is 50mm, and connected to it is a W/M, D/W, 3 x sinks and shower/bath.

    Should the waste pipe be larger than 50mm, and is this the reason why it keeps getting blocked?

    Any advice much appreciated.
  2. Best

    Best Trusted Plumber Top Contributor!!

    If it is getting blocked, then it is to do with something being put down it - like food or grease down a kitchen sink, for example,
    - or, more likely your waste pipe in wrongly installed and doesn't have a correct fall, not clipped and sagging somewhere, etc, allowing waste to fill with water causing an airlock and/or blocking with hair, soap or other.
    • Agree Agree x 2
  3. oz-plumber

    oz-plumber Plumber

    With all those fixtures connected - no wonder it's blocking.

    Saying that, very unlikely that all fixtures are being used at one time.

    Could be down to a gradient issue, no: of bends & junctions, length of drain and venting issues.

    The drain design doesn't sound desirable but there are many factors that could make the drain not work at all
    • Agree Agree x 1
  4. Ric2013

    Ric2013 Plumber Top Contributor!!

    Agree with comments above. Not a great idea to use 2" pipe for all of that and may be slow if you're trying to use all those appliances at once, but shouldn't actually block. Could be as simple as someone hasn't bothered to deburr the internals of the pipes at joints and hair etc is getting caught on them. Or, as Best says, not properly clipped or sloped etc.
    If it's blocking, are you able to find the exact place it blocks up?
  5. Charlie080

    Charlie080 New Member

    Ok, thanks. The pipe is going to be re-run to provide a greater fall and reduce the number of bends. Hopefully this will reduce the likelihood of it block again.

    All advice appreciated.
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