As far as re-using, I'm not sure. I don't know if I'd go so far as to claim a bottle a day to be 100% OK, but I would certainly argue that a bottle every other day isn't going to hurt. This is based on my own analysis of published research and experiments from the last 60 years available online. It's worth spending the time to analyze yourself if it's of concern, it's actually somewhat interesting I think, and of course I'm not a medical professional so you shouldn't take my own analysis without question.
Here's some links:
(WHO information/findings with summary. Examines mice, rats, dogs)
(lots of raw experiment data based on mice and rats.)