Hopinso is right in my view in endorsing distilled water on a fast.
However, this water WILL leach minerals from the body, but only the inorganic minerals that have not become a part of the cell-structure, and are of no use to it, as opposed to the organic minerals that do........ http://www.aquaprix.com/resources/from-dr-andrew-weil/
To be absolutely clear about this, distilled water is what we receive in the water-cycle: evaporation, then condensation followed by precipitation, in other words pure H20. Atmospheric pollution however, makes this distilled water as unfit to drink.
Distilled water then is the same water that we receive in the water cycle, unless as someone once commented: "God made a mistake".