[Greenbuilding] history of toilet flush volume

[Reuben Deumling]

I am curious if anyone on this list might have insights on this subject?
Since 1992 toilets in the US have been required to use no more than 1.6
gallons per flush. Prior to that many toilets used more water. How much is a
matter of some dispute, though I have measured 3-4 gpf. What I am interested
in is a historical overview of the changes in flush volume prior to 1992 in
the US. My suspicion is that, like with washing machines, refrigerators, and
other (major) appliances, the amount of water and/or electricity these
devices used was jacked up during the Cold War for ideological and economic
reasons. In other words that toilets, like fridges and washing machines,
actually may have used modest amounts of water (for flushing) before WW II.
Can anyone point me to sources that would help answer this question?

Thanks.

Reuben Deumling