My city tap water does not have any chlorine or chloramines. So it is already pretty great although it does have fairly high alkalinity. I brew light pilsners with 50/50 or 75/25 RO/tap water, and occasionally for other beers, but mostly rely on tap water and phosphoric acid (for lighter beers) to get my pH down into range and still end up with very good beer. That is to say, unless brewing a beer that really benefits from soft, mineral free starting point, I just manipulate my tap water so long as that stays within the guidelines for treatment without adding undesirable flavors. I don't like the hassle of purchasing bulk water for my 11 gal batches. I have learned to use plastic, not glass carboys to transfer RO water from the store!