I know what your saying Izzy, I've had good luck with mine, I've traveled with it and haven't got sick yet. I carry back up batteries and remove the batteries when not in use but I used the heck out of it when traveling and went through a set of batteries in a day by cleaning up the water including for brushing teeth, etc...
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Failure is not an option!
USMC Jungle Environmental Survival Training PI 1985