We are looking at putting in a RO water system in our house. We have well water that is not only high in calcium, but also has some sulfur smells and iron in the water. Iron, I have heard, is a no no for good brewing water. We don't drink it, we can, but tastes odd. Odd water will make odd beer, I can almost guarantee that. I tried Softened water from the winery (where I work) and that has too much sodium and enhanced the hops bitterness into an unacceptable after taste bitterness.
Last couple of batches I used distilled with some regular water that is bought that has minerals, but no sodium. Ozone treated, etc. Last batch was mostly distilled so added 3 grams of calcium chloride to the mash just to give it some calcium. Fermenting nicely..
Anyway, what is it like to just use home well water that has been Reverse Osmosis treated? It is touted as removing iron, calcium, etc so I would imagine a lot like softened water, without the sodium.