I am a occasional bike commuter. Drinking with the water bottle inside the bag is quite difficult as you are to open it, get it, drink, put it back in the same position, etc. Therefore, it is not uncommon that the water leaks from the bottle and soaks all your stuff. It could be avoidable with a mesh or similar bottle holder on the inside of the bag or a velcro attached bottle holder on the main strap of your bag.
Going beyond, two years ago, I sent a mail to Camelbak suggesting a hose that allowed you to drink from a bottle in the way of the ones that allow you to drink from the bladder. I don't know if it had anything to do with it, but Camelbak released ot to the market.
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