Jeeze, ya thats a rough 1. Im glad that does not happen to often, it wont deter me from swimming in the lake by my house because its a great lake, but I suppose anything can happen.
When camping at least a few times in the past I have had to rely on water from the environment, sometimes i truly trusted the source and had no problem collecting and drinking it right their, but if you are not 100% certain that water is good definatly boil it and filter it out the best you can!
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DX'ed with HFA as a child. However this was in 1987 and I am certain had I been DX'ed a few years later I would have been DX'ed with AS instead.