SAFE FROM BPA's The AQUATANK's inner lining is 100% food-grade TPU (Polyurethane) and the outer shell is durable nylon. Aquatank is the safest, toughest, and lightest bladder on the market! PEACE OF MIND WATER STORAGE -- With all of the events happening in the world right now, having a large amount of drinkable water storage is incredibly important.