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

Step 2: Time to Cover Up!

First, to properly cover the bladder with Duct Tape you must inflate the bladder for a sort of "template". If you dont inflate it and cover it while its empty, it wont expand when you fill it! So, inflate the bladder, and block the air flow. Cover the bladder throughly with Duct Tape, leaving holes for the filling hole and hose hole. I added a handle for hand carrying.

Step 3: Backpack Straps!

Now, add backpack straps. Take a piece of duct tape that is long enough and fold it in half to make it not sticky. Adjust, add, or snip off some tape to make it fit you well. then attach using a strip of duct tape. Also, i added a little holder for the strap so it doest fall when you let go of the nozzle.