I buy a big tub of whey protein and some 12 ounce water bottles. Funnel a scoop or two of whey into the water and take it to work. 6-7 hours later, I drink it.
question: does it damage the protein being in the water that long?
Personally I wouldn't do it. If I am getting a shake ready for later I keep the powder in a sandwich bag then just empty it into the water when needed. That way it doesn't matter if the water does affect it