Originally Posted By Robotmoose
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I was also always scared to use it because I could never work out how to purify the water outside my dromedary bags after they'd been filled: the water not in the bladder, but along the mouth and near the opening could cause major contamination problems.


When you go swimming in a lake, how do you purify the the water the splashes along your mouth and near the other openings? I would use that same technique.

All sarcasm aside, a drop of contaminated water does not render a whole bladder unfit for consumption. The nasties need a critical mass to make you sick. If you are really concerned about it, just unscrew the lid slightly, turn the bladder upside down briefly, and use treated water to clean off the contaminated water.