reply to PoloDude
Re: How to determine GPF of existing toilet?
said by PoloDude:Woudn't take into account the water that goes down the refill tube into the bowl, which may or may not continue to run for a while after the bowl is actually full, wasting water down the drain.
Get a gallon container.turn off the water to the tank. Flush the toilet. Refill the tank using the gallon container. do the math.