I am looking for a way to carry extra water, 2-4 gallons, on a trip that I am planning on. I would like to carry extra water because water is not guaranteed to be available for a couple of days of the trip. I have thought about using 2-3 liter bottles, but they are bulky and take up alot of room in they panniers. I am wanting something that will let me maximize the amount of water I can carry while minimizing the space they take up.
This trip will be self supported, camping along the way. It will be 7 days of riding, covering 280 miles in upper 90 to 100+ degree weather.