Does the bottled water say what its contents are. If it is RO water without any minerals in, it won't be good for fish as very very few fish can live in mineral free water. You have to add minerals back in to make it safe for fish, usually called smething like remineralisation salts. I'm afraid I don't know what makes are available in the US. Though it is possible the bottled water have had something added, I would check the label. I think someone once said that a lot of US bottled water had plain salt (the kind you cook with) and sugar added, but I couldn't swear to that being true.
For a 10 gall tank, I would add 1 gall now, then in a few hours add another 1 gall and so on, but don't change more than half the water in total. That won't get your nitrite down by more than a bit, but you will still have some minerals left. Then asap find a shop that sells remineralisation salts. I know that Kent marine sell something called RO right, and I think they are an American company (their products are sold in the UK) and there will be other companies that I don't know about.