Water System sizing chart

Does anyone know, or can tell me where I can find a more current water system sizing chart based on fixture units and GPM. Here's the problem I'm having: I don't believe there is a more recent chart available reworking and lowering the gpm values for the 1.6 GPF water closets vs. 3.5 GPF water closets.

i'm not a flush valve expert, but could those values possibly not change, because you still flush the same amount of water GPM-wise, but for just not as long ?

I'm not aware of an updated version but I understand this is going to be a future ASPE Research Foundation project

One other thing to consider is that the tables or values prescribed by the code may not be in line with the new values regardless of how much sense it makes. The officials have to follow what the code dictates.

My plumbing code here in Kentucky does not have sizing requirements, nor does the International Plumbing code. Uniform Plumbing code has a section for sizing domestic water that would make anyone's head spin !!! :oops:

There ought to be a way to size domestic water more acurately, per application. If you were to have 6 flush valve water closets scattered everywhere in an office environment, in "one-holer" configurations, you may get by with 1-1/2" minimim. if you have those 6, all in line in one restroom, in an assembly type application, I'd rather put in a 2-1/2'' service and plan on any 4 of them flushing at once.

Hospitals are different than schools, schools are different than theaters, etc.... there ought to be a better way than a standard 10 fixture units per flush valve, which is generic and suppose to cover them all. The same can go for sanitary sizing, which can be easily undersized sometimes if sized "to code"... but that's a whole 'nuther subject.

National Standard Plumbing Code 2000 appendix B table B.5.2. contains values for low flow fixtures.