I use tap water for everything. There are a lot of negatives, but there are also nutrients that are not present in distilled. For fish of course I use start right and pro clear because fish are pretty sensitive to high levels of chlorine. I used to waste my time filtering water and what not, but then thought to myself "What would they be drinking in the wild?". Could be worse.
In my opinion if you don't have overly contaminated, hard water I would just use tap.