(Kelly of the Clue Crew reports from  White Sands National Monument, New Mexico.)  In desert conditions, you need at least one gallon of water per person per day, have reusable water containers, & a tincture of a small percentage of this to purify the water
Sizes range from small single serving bottles to 
large carboys for water .... By one estimate, approximately 50 billion bottles of 
water are consumed per year in the U.S. and around 200 billion bottles globally.