I'm trying to figure out how many water supply fixture units (WSFU) can fit off of my CPVC supply lines. I looked at the tables in the 2015 NSP , but where I'm confused is figuring out where that is calculated. Example -

I have a 3/4" supply line that tees to two 1/2" branches. On one branch I have a dishwasher and kitchen sink, and on the other I have a bathroom with a 1.6gpm gravity toilet and a sink. I'd like to T the connection to the bathroom so that it'll have 1/2" going to a bar sink and the other 1/2" going to the bathroom as before.

The question is, when doing the calculation, am I looking at only the WFUs off of the 1/2" line that is going to the bathroom, or do I have to take into consideration the line that is going to the kitchen as well?

   main =========T------------T---------- Bar Sink
                 |            |
              kitchen       half bath

        = -> 3/4"
    - & | -> 1/2" CPVC SDR11
        T -> tee intersection 
  • The toilet is presumably GPF (gallons per flush), not GPM (gallons per minute.) – Ecnerwal Apr 2 '17 at 21:26

At the 3/4" main you look at everything beyond that (i.e. everything, for this question.)

Everywhere else you look at everything beyond that - so once you pass the Tee for the kitchen, the 1/2" side feeding the kitchen is looked at for the kitchen devices, and the 1/2" side feeding the half-bath and bar sink is looked at for those devices.

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