Whoever came up with the idea of carrying potable water within your backpack is or was a genius, that's all we have to say on the matter. Other than that you can make sure that you're kept hydrated the whole day long with clean and safe water with one of these backpacks from such great brands as Osprey and Camelbak.
Camelbak Rim Runner 22 Hydration Pack 62569
Camelbak Mule NV 100oz 62399
Camelbak SnoBlast Hydration Pack 62493
Camelbak HydroBak 50oz Hydration Pack 1122001000
Camelbak Lobo Hydration Pack 100oz 1118001000
Camelbak Mule Hydration Pack 100oz 1115701000
Camelbak Kids' Mini M.U.L.E. 50oz Hydration Pack 1155601000