Supply line sizing for master bath dual lavatory + toilet

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by PC7060, Dec 9, 2013.

  1. PC7060

    PC7060 Handling one headache at a time

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    Dec 9, 2013
    Occupation:
    Design / Engineering
    Location:
    Northern VA
    I've looked up the fixture units for lavatories and gravity feed toilet for Virginia in Table 2903.6 at:

    http://www2.iccsafe.org/states/virg.../Chapter 29_Water Supply and Distribution.pdf

    This table define the fixture units for each lavatory at 0.5 and toilet at 2.2 for a total of 3.2 fixture units; can I supply all three fixtures off of a single 1/2" copper branch off of a 3/4" copper line? House pressure is regulated to 80PSI.

    Thanks in advance.

    PC

    PS: The folks at JohnBridge forums say hi! :cool:
     
    Last edited: Dec 9, 2013
  2. Stuff

    Stuff Well-Known Member

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    Pennsylvania
    In your link look at TABLE P2903.7. Maximum of 3 water supply fixture units for 1/2 distribution pipe.
     
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  4. PC7060

    PC7060 Handling one headache at a time

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    Stuff - Very good, thanks for the quick response! Can't belive I missed that, must have been a "can't see the forest for the trees" thing. :)
     
  5. PC7060

    PC7060 Handling one headache at a time

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    Followup question - what is the fixture unit so high for a toilet? For example a shower is 1.0 fixture units but the toilet is 2.2. Seems odd.
     
  6. Reach4

    Reach4 Well-Known Member

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    In table 2903.6, it says that a toilet and bathroom sink combined is 2.5 wsfu of cold, 0.5 of hot, and 2.6 wsfu if combined.
     
  7. Stuff

    Stuff Well-Known Member

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    Location:
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    Good point. I sometimes can't see the forest for the trees either.


    As for why it is so high, look at TABLE P2903.1 to see that you are required to supply a one piece toilet at 6 gallons per minute! My guess is that it has something to do with making sure that the shutoff valve closes properly. Hopefully someone else has a real answer.

    Terry's chart is a bit more realistic - https://terrylove.com/watersize.htm
     
  8. PC7060

    PC7060 Handling one headache at a time

    Joined:
    Dec 9, 2013
    Occupation:
    Design / Engineering
    Location:
    Northern VA
    Interesting, thanks for pointing this out Reach.

    Since I have dual lavatories; adding the 0.5 for the second lav bring the total to 3 which can all be supplied with a single 1/2 branch per P2903.7 with 80PSI source

    Certainly seems reasonable since a full bath group, toilet, lavatory, tub w/wo shower is listed as 2.7 for cold line in 2903.6.

    Thanks again for your assistance.
     
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