you can find RO, RO/DI, water in any grocery store. Just make sure you read the label. It will say, "processed by reverse osmosis",or the same that has been run through a deionizer. I bought my own RO/DI unit from spectrapure. I never have to leave the house to get water.
Distilled is a bad idea. While it is germ free, it has a high concentration of copper, as this is the conduit used to do this. Remember pictures of stills in the country. They use copper tubing to run a still. This is the same process that is used in distilled water.
Hope this helps!!