My DME told me today that if I couldn't find distilled water, I could filter water and boil it. I guess the filter would remove most of the minerals and chlorine and other icks (I don't think any home filter does 100%), and boiling would take care of the microbial concerns. However I know that's not the same as the distillation process, which makes the water truly pure, but it might work as a stop-gap.
DX 7/22/10, started treatment 8/25/10
REMstar S1 Pro C-Flex+ / Swift LT for Her mask, 9/14/10
RemStar S1 Pro DS 550 Auto 3/20/12
Usual pressure 4-8
AHI before CPAP, 26; now .7