[Greenbuilding] history of toilet flush volume

[Frank Flynn]

> Given the historical sizes of toilet tanks, I have some difficulty
> believing
> the 7 gpf figure as an average. 7 gallons is very nearly a cubic foot, and
> I
> should think that would require the portion of the tank below the water
> line
> to be at least that voluminous. I say at least because it is not uncommon
> for US toilets to flush in such a manner that the flapper drops back down
> before the full volume within the tank has been drained away. Can anyone
> confirm the existence of a 7 gpf toilet? or recall toilets made before
> WWII?

Don't forget that most older toilets dump 1/2 of fresh water down the over
flow tube while filling the tank.  On most older toilets you can see this
if you take off the top and watch it flush. They do that to ensure the
bowl is filled.

I've never measured the actual volume but I have had an older one and 7
GPF does not seem far off; they use a lot of water compared to a new low
flow one.

Frank