I remember,  as a kid,  going hiking with my dad.  We happened upon a
stream with a stone bed and it was clear,  cool,  fast moving water.   I
remember my dad telling me that the rocks actually filtered the water and
that it was safe to drink.   I know he was not correct,  but I sure wish he
was.   It seemed like nothing in the world tasted better than that water.
Oh well,  it didn't kill me.

Doc