Here distilled and deionized water must be respectively labeled in a distinct manner. I use only real
distilled for unusually fussy or pH-sensitive work like matched separation negatives, as well as for
final rinse of negatives with Photoflo. But our tap water here is so good that I use it for anything
routine, including conventional black and white developers. Stored concentrates are always mixed
up with distilled, however, just in case. Our city water is largely snowmelt piped in directly from the
Sierras. But there are plenty of other places in the state where either the mineral or chlorine content would make it unusable in the darkroom.