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 Mule NV 100oz 62399
Camelbak Pursuit 24 LR Hydration Pack 62197
Camelbak Kudu 12 Hydration Pack 62453
Camelbak Women's Spire 22 LR 100oz Hydration Pack 62461