I just fill my bottles with heavy water. It's about $1000 a liter, so I figure it's just got to be better.
Seriously, the amount of water I carry on the same route will be different from day to day because of the weather. Running out of water at 95 degrees and no place to fill a bottle for 20 miles is a mistake you really don't want to repeat. I sure as heck am not going to tell someone else how much water they need to carry.