upsize tub drain

Discussion in 'Shower & Bathtub Forum & Blog' started by Rocknroj, Feb 24, 2009.

  1. Rocknroj

    Rocknroj New Member

    Dec 30, 2008
    I am replumbing waste lines and am wondering if upsizing the trap for my tub/shower makes sense.. It is usuallly used as a shower and I don't want to worry about hair clogs.. While showers call for 2" waste, the tub shower kits are always 1 1/2.. So I was thinking about upsizing to 2" on the tailpiece and then connecting 2" trap, trap arm to the 2" drain. The old pipes (iron) clogged a lot..

    Does this reduce the effectiveness of the drain to self clean? The inspector said I only need 1 1/2 , but is there anything wrong with oversizing in this method?

    Thanks in advance

    Picture attached

    Attached Files:

  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    I think you would be wasting your time and money. The reason a 2" drain is required for a shower is that if it was just a 1-1/2" drain and bcame becomes even partly clogged, you'd have a flood. The larger 2" drain gives much more opportunities for the water to drain. If the tub drain clogs, you have the tub itself to act as an emergency catch basin. I have a tub-shower combination, 1-1/2" drain, that has never clogged in 37 years. Your tub is designed for a 1-1/2 drain so to go larger would require figuring out how to cut the tub outlet larger and finding 2" drain hardware.
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    I, and most plumbers, do run a 2" drain to the bathtub, but since the water flow is determined by the tub drain fitting, not the drain pipe size, it is strictly to provide long term service. Your tub will not drain any differently regardless of the pipe size.
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