I had anodizing shop doing mostly R&D for a chemical manufacture for a last couple years. Rather than using distilled water, we used reverse osmosis system as well as deionized water. Deonizing systems are a little pricey, but there are companies that will lease the equipment. I had very good results with with the RO system for removing the dissolved solids. Basically, I was running the RO system while running the line and stored the processed water in a 800 gallon tank. I could fill the tank in about a day and a half. The RO system was around $200, I bought the tank off of craigslist for $100, and had a harbor freight pump. I added a inline meter to monitor dissolved solids, mostly to know when the filters had to be replaced.
Eric