Water To Go is who I use exclusively when I buy RO water. There is a store a few miles from my house and their RO setup is impressive. I have been very happy using them. The store near me has a deal where it's cheaper if you buy 100 gallons (in credit) at a time.
Naturally, since there is no minerals in the water, I add salts or mix filtered tap water to achieve a desired mineral profile.
Uff Da Picobrewery
Kegged: Vienna Lager, Mánagarmr Stout, Ratatoskr IIPA, Cider
Bottled: Yule Gruit