purification

Hi All, Unfortunately I still have the original aluminum tank in my E31 and will not replace until next year. I was searching the post and could not find anything for purifying the water when using an aluminum tank. I once read that you can't use bleach for purification water for aluminum...

What do you all use for water purification addatives in your fresh water tanks? Anything work better than the others? As our cruises get longer and longer, we find ourselves actually drinking and cooking with this water--- it would be nice to be sure it's safe. Thanks, Chris