I want to purchase some type of water filtration system to produce water that contains negligible amounts of minerals. Currently I purchase distilled water from Walmart, and I want my water filtration system to be that good.
I was under the impression that a standard home reverse osmosis system with a carbon filter would do this. However, MoreBeer states:
Reverse osmosis. Reverse osmosis (RO) involves passing water through a series of individual pressurized membrane filters that remove organics, inorganics, microbes, and some minerals. The “bulk water” machines frequently found in grocery stores often use reverse osmosis to treat the local water and usually carbon filter it as well; this water usually sells for $ 0.25–0.35/gallon. It is essentially similar to very soft spring water or distilled water.
I am confused because they say it removes "some" minerals, but then state that the R.O. water you buy at a store is "essentially similar" to distilled water. It goes on to imply that Deionization/Ion Exchange would remove all the minerals.
If I really want to get 0ppm water (or insignificant amounts of minerals), would a reverse osmosis system be sufficient, or would I need an additional ion exchange component?
[Edit: added the term deionization, which apparently is different than ion exchange]