I will take that as a "YES" to my question! I gather that you should be as exact as possible to treating the entire water you have stored.
I just thought there might be some leeway considering the fact that some people store water with no preservative added at all. I thought that if 75 to 85% of the water was treated it would be enough to treat the water much, much better than nothing!
But I do understand what you are saying about water being the most critical single item needed in a survival situation.
Thanks for the info.
Land of the Free Because of the Brave!
It is easier to be critical than correct and most people tend to take the easy way!