Most tap water is fine to use for brewing, even if your water is hard as this provides minerals needed to the yeast for a healthy fermentation.

Carbon filtered water is perfect to use, even water treated by reverse osmosis or ozonation is fine, although softened water is less desirable as it can contain higher levels of salts.

Only water that is high in iron or chlorine should not be used. The abundance of these minerals can lend off flavors to your finished beer.