There is a slit in the blue or black cap on the end of the tubing. The slit needs to be opened up before using the bladder the first time. Then you just bite down on the cap and it opens the slit so you can suck water out. If you took this cap off then you are likely just loosing the water out the tube as you ride.
The bladder needs to be placed in the camelbak with the tubing at the bottom and the fill port at the top, otherwise you will suck air until all the air is out of the bladder. Then you have to suck harder to get any water, since you do not have water pressure helping push the water into the tube.
After filling the bladder 3/4 full, hold the bladder upright (fillcap portion up) and screw the cap on.
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