I have a Steripen Classic. For it I have a 1 quart (946 mL) Powerade bottle, but I'm considering getting a Nalgene bottle which is advertized as 1 quart, but shows measurements up to 1 liter. Which of these would be best? Part of my reason for asking is the size of the mouth of the bottle (avoiding touching the side of the mouth with an untreated water container), but I realize that there may be other things to consider, such as the measurements on the side of the Nalgene.