How small can I go on a toilet waste line, and how far can the vent be from the closet bend?

8 Answers

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  • Anonymous
    7 months ago

    There is 3" but I don't know why anyone would choose it. The vent is normally in line with the closet bend.

  • John P
    Lv 7
    7 months ago

    In Britain 4 inches for toilets without macerators, i.e. nearly all toilets. I spent a recent public holiday helping a neighbour to unblock a common drain run to the pubic sewer. It is a 4" drain, so even that can get blocked if people put big stuff such as nappies (diapers) down it..

  • 7 months ago

    Unless you're using a macerator (brand name like Saniflo) don't go under 4 inches. A huge man dump can block anything smaller. The vent can be a long way from the nearest bend.

  • Droopy
    Lv 5
    7 months ago

    Something you don't want to cut corners on a crap pipe. Go 4" or your chances of having to clean a crap pipe increases. Course if you like playing in human waste get a macerator or use smaller pipe.

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  • Anonymous
    7 months ago

    4 inches if gravity-fed. You can use a macerator but they are noisy in use and are something else to go wrong. Vent depends what else is connected to the line. If you are going single-stack you shouldn't need one if you are within 20ft of the vent stack.

  • 7 months ago

    4" is standard in most western countries ...but with a saniflow mascerator it goes down to an inch ..with flexible pipe ..as for the vent ..most vent should be above the highest opening window ..no lower ..but you can fit a durgo valve ..now either interior or exterior ..its a self venting valve and should be no lower than top of wash hand basin ..can be boxed

  • bond
    Lv 7
    7 months ago

    In some situations a 3 inch can be used. Don't really understand your vent question.

  • 7 months ago

    the waste line NEEDS to be full size as determined by local plumbing code. that's frequently four inches [10 cm].

    vent needs to be within distance specified by plumbing code as well .... you local permit office will review your plan and tell you if you're good -- usually for free since you already paid the permit fee

    Source(s): grampa
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