[Greenbuilding] 2" drain line for a 0.8gpf toilet?

[Reuben Deumling]

Here's a study that suggests 0.8gpf is pushing things* in a 3" drainline.
http://www.allianceforwaterefficiency.org/uploadedFiles/Resource_Center/Library/residential/toilets/Drainline-Transport-Study-PhaseOne.pdf


* or rather failing to do so reliably

On Sun, Apr 24, 2016 at 3:29 PM, Reuben Deumling <9watts at gmail.com> wrote:

> I have long wondered whether or when anyone would dare diverge from the 3"
> standard drainline diameter as we get toilets that use less and less water
> per flush.
> Interpolating from this chart:
> http://www.mpwmd.net/rules/Apr2008/pdfs/RegII/rule24_table1.pdf
> I see that in terms of fixture units, a 0.8gpf toilet is now at 1, which
> puts it comfortably within the same class as sinks, which as we know do not
> require anywhere near a 3" drainline. So..... does anyone on this list know
> if there is any movement toward allowing a 2" drainline for a 0.8gpf
> toilet? Or whether there's been any testing of this configuration?
>
> Reuben
>
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