RO vs Distilled

[atomicpunk]

Is there an end difference? I know there is a process difference.

If I am diluting my tap water, which is very hard, does it matter if I use RO or distilled?

If I want to build up from scratch, which to use?

[JohnF]

The ionic content of RO can vary as the filters will remove X% of ions so water with many ions run through an inexpensive RO unit may produce very different water than portland water run through a very good RO unit.

Other than that, they are both usable for building water for brewing. I am comfortable using 100% RO but might blend in some tap water if I used distilled because I would worry about some trace minerals.

RO water tends to be quite a bit cheaper and can be bought in bulk which is convenient.

[beltbuckle]

Either will work fine. RO / distilled / De-ionized water is all very similar. I have tested numerous RO water and they all tested less than 10ppm of total dissolved solids. That's close enough to zero to not really be a factor for brewing.