I agree that you shouldn't use distilled water. If you're really worried about missing a water change, you could use bottled spring water (available at nearly any store - typical bottled water). Unlike distilled water, it does contain some minerals.
Notably, boiling water does not remove its minerals. It can, because of evaporation, concentrate them. This is why, if you live in an area with hard water, you observe mineralization in your kettle over time. What boiling does do, however, is kill potentially harmful bacteria.