The clear running mountain stream is an iconic image of purity. Think of every advertisement for bottled water you've ever seen. So naturally when our heroes are hiking through the wilderness and they come across a babbling brook, it's time to dive right in and drink their fill without a second's thought right after filling the canteens. Those of you who are regular campers or have attended any form of survival training know where this is going. Also see I Ate What? Examples of Cool, Clear Water include: