5 gal. Water Bottles are polycarbonate. The same plastic as nalgene bottles. I use them when I run out of glass ones.
Polycarbonate (PC)
Crystal clear, strong and rigid, polycarbonate is autoclavable, non-toxic, and unbreakable. FDA approved for Food and Drug applications, this resin is the toughest of all thermoplastics, but is soluble in various organic solvents.
Polycarbonate is ideal for high temperature applications and can also withstand low temperatures. It is commonly used as 5 gallon water bottles and reusable 8 oz. school milk containers.
Lexan is GE's tradename for Polycarbonate. PC is an expensive material.