The first thing you should do upon getting your CamelBak is wash it. After all, you don't know who or what touched the pack before you purchased it! If washing it normally doesn't remove the plastic taste, you may want to soak the inside of your CamelBak in water with about a teaspoon of baking soda dissolved in it. After letting this mixture soak for about an hour, rinse out the pack. Your CamelBak should have no more plastic taste!