It keeps flies and skeeters and their larvae out of the water. Which for me is worth the $20 backup to my four 55-gallon plastic drums in the celler. And the 2 and 3-liter jugs in the pantry. And the 400-gallon *water buffalo* trailer parked behind the deuce-and-a-half. But parked empty in the wintertime.
Redundancy brings comfort, but should not generate complacency.
Do you know how to make water from open streams safe to drink? I know that ground water is not safe but in an emergency situation would it be possible to make it drinkable?
Water Buffalos are great.