Remove the water reservoir from the backpack.
Fill the water reservoir with your desired amount of water.
Eliminate the resulting air pocket in the water reservoir by resting it on a flat surface to seal the cap. Allow the water level to reach just below the cap threads as you tightly screw the cap back on.
Insert the water reservoir into the backpack and thread the flexible drinking tube through the hole located near the top of the pack.
Loosen the shoulder straps on your CamelBak backpack and put it on. Tighten the shoulder straps until the CamelBak feels secure and comfortable on your back and shoulders. Some variations have adjustable sternum and belt harnesses as well.
Locate the drinking tube, which varies among different models. Some will place it over your left shoulder, some over your right shoulder, and some styles let you choose which shoulder. A clip on one of the shoulder straps allows you to secure the end of the drinking tube with enough slack to reach your mouth. Have a cool drink.