I make my own distilled water these days. I have a steam juicer, it's like a triple-decker boiler. The bottom has the water, the middle is the pot that catches juices (steam moves through a volcano-shaped central spout). The top is the colander that fruit or vegetables are put in. Instead of putting anything in the top I fill the bottom with water, put rest of the pot in place, then put the lid on upside down so it's a shallow dish. Fill that with ice cubes and the steam hits that lid and drips as distilled water into the catchment pan. (That pan has a hose for decanting liquids). It's a complicated description of this pot. They're expensive enough that you can probably buy about 75 - 100 gallons of distilled water for the price.

If you don't already own one there are other ways to make it at home. Depending on how much time you have, etc. It doesn't take long, and you may not want to bother in general, but this will work in a pinch when you're out of water and don't want to run to the store.

Here's another article how from Wikihow.