I'm on a well and use distilled water to mix my chemistry and for a final rinse. Here I can get a gallon in my local supermarket that claims to be steam distilled for $0.79. Since I do mostly 120 films one-shot in HC110 and infrequent printing, the cost isn't important enough to experiment too much. Interestingly, I used to see a lot of rusty iron deposits in the toilet tank and such here, but since replacing the well pump a year ago, which replaced the iron well pipe with plastic, a lot of that has disappeared. Might have wished I'd done it sooner, except for the $3K!