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Discuss Bath and shower drain installation in the Bathrooms, Showers and Wetrooms area at

  1. JamesT

    JamesT New Member

    Hi All,

    I am currently installing a new bathroom and the stage where I want to install the drainage from the shower and bath.

    I am running the bath drain in 1 1/2" and the shower drain will tee into this. Both have bottle trap like traps.The pipe will eventually the into the soil pipe outside.

    My question is; is there any problem with the length of this drain leg as it will be approximately 5m long? Will I need to put a durgo on or something to prevent the trap from siphoning out?

    Little guidance would be much appreciated

  2. JCplumb

    JCplumb Plumber

    According to the regs, 40mm isn't big enough for a 5m run, neither is 50mm. You'd need 3inch to satisfy the regs for a 5m run.
    That said, I've seen 40mm waste runs of that length that have been fine for years, although you are also tapping a shower waste into the run, so you're really pushing it tbh.
    I wouldn't use bottle traps on anything other than basin wastes or urinals, on a bath they can mean the bath empties noticeably slower than with a P trap or standard bath trap, especially when they start to get soap and hair lodged in them, which they will.
  3. king of pipes

    king of pipes Trusted Plumber GSR

    As above 11/2" pipe is not big enough you need 2"over a 3m run , its better to run each of these separately as there is always a risk of the bath water coming up in the shower waste when you empty it , where is the basin waste going ? Kop
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