Heres a little 'ible on how to make a Duct Tape Hydration pack on the cheap instead of going and buying a camleback which usually cost upwards of 100 dollars.
Step 1: Materials!
You'll need a roll of duct tape (Duhh!!!)
and you'll need a water bladder, hose, and nozzle from a camleback. Now i'm using parts from an old hydration pack, but you can buy your parts online. They may cost a fair amount, but trust me, its all much cheaper than buying an actual camleback.
Heres a really cheap bladder online that i found - http://www.rei.com/product/767109