Can you drain a washing machine (only) with 1 1/2'' pvc , my inspector says it must be 2'' ?

Discussion in 'Illinois Plumbing Code Questions' started by sawhorse, Aug 15, 2016.

  1. sawhorse

    sawhorse New Member

    Aug 15, 2016
    Code says laundry machine has a load value of 2(DFU) and a 1 1/2 pipe has a load rating of three so why a 2 inch pipe ?
    Last edited by a moderator: Aug 15, 2016
  2. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    Many newer washers pump the water out faster, so hence the code thing. 1.5 may or may not work OK with your washer.
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  4. Cool Blue Harley

    Cool Blue Harley One Dumb Plumber

    Apr 16, 2016
    San Francisco, CA
    Clothes washers are normally rated at 3 DFU each. Clothes washers in a battery of three or more are rated at 6 fixture units when sizing the common horizontal and vertical waste pipe sizing to take into account the possibility of simultaneous discharge and the suds producing effect in the drainage piping.

    A 1&1/2 inch pipe is rated at 2 DFU vertical and 1 DFU horizontal.

    A fixture unit is a numerical load factor which measures on some select scale the load-producing effects of a single plumbing fixture of a given kind.
    Terry likes this.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    It makes no difference whether a 1 1/2" line can drain the washer, because you are not going to get it approved until you satisfy the inspector. But, almost, if not all, codes do call for at least a 2" drain for a washer.
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