In Utah from the Hite Recreational Area to Blanding is a 73 mile stretch with no services. I had three gallons of water when I started, but at the bottom of each major grade I'd dump a gallon when I realized that there was no way I'd be consuming it. It was probably in the 40's (F) all day and I probably drank no more than about a quart. Carry more than you think you'll need and dump some when you are certain you won't need it.