Actually, the chlorine dioxide tablets release oxygen which does the purifying. ClO2 is quite a quite different compound from household bleach, sodium hypochlorite.

However, I've occasionally noticed a residual chlorine taste after using ClO2 tablets, which doesn't exactly taste good. That and the long treatment time needed for protozoans is why I use them only for emergency backup.

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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey