I work in the construction world and we use compressors all the time we drain ours every day but most guys do not. I have drained other guys stuff and they are half full of water and green slime which will not only rust the tank but trash your air tools. My uncle worked for a trucking company that had a big three phase compressor in the shop and it exploded one day as he was walking by and almost killed him this is a serious topic they rust from the inside out.
