what water is best

bang guy

Moderator
Rain water should absolutely not be used. If you think it's clean, think again. All the pollution in the air gets used as a condensing surface.
Try this just for fun. Put out a clean glass next hard rain. once it has a significant amount of rain water bring it in, cover with saran wrap and let it sit 24 hours. Now... look at the bottom of the glass.
 
Top