Join Date: Jul 2010
Location: Outside Philadelphia, PA
Considering that they charge you a dollar or two per gallon of water, tap water can be a very low cost alternative. I'd use that, unless I had a specific issue with my tap water. For example I have a friend that has to have a whole water treatment plant in his basement because the well water is so bad.
If can't use tap water, and you'll need more than a few gallons, consider getting you own RO unit to make pure water for you. If you go that route, you'll need to use GH and KH additives to get the GH and KH to where you want it.