From actual use I would say 1 tablet for 1/2 liter of water would make it very unpleasant to drink. I find the chorine aftertaste quite noticeable at the regular strength. Doubling the dosage IMO would make it very hard to swallow.

Adam
Wel those survival-rations don't taste like a 5-star dinner either, but they do keep you alive...

IOW: sometimes you've just got no choice..

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''It's time for Plan B...'' ''We have a Plan B?'' ''No, but it's time for one.'' -Stargate SG-1