Hard question - are you thinking about saving it up for winter? You couldn't save that much without a very big pool I think :-). But a few weeks, or even a couple of months if it's kept clean, should be ok. A lot of people keep their tap water for a few days so that chemicals can leach out, but that's not the same thing. I don't know if the good things about rainwater will still be good after a long time or not. Someone should research that.

Thanks for your input Lucy. I wanted to save at least a few bottles for the winter. I guess if it smells bad after a while, I should throw it out. Thanks again!