Right now I collect the cleanest snow from my back yard, melt it down in a big pot, boil it for a few minutes, and then strain it through an old t-shirt. *It's worked well so far. I'll be buying distilled water soon though. I haven't gone to the grocery store in a while.
It's not purified but it's the best I can do for now. I hope to get a job soon and then my parents will have to let me get an RO water system.