Innovative Steam Technologies has a engineering specification on the Web for once-through steam generators. Search using "feedwater guidelines". I have a copy and may be able to email it for you.
I have experience with draining a demineralized water tank to the environment in the state of North Carolina. Our division of water quality has allowed us to drain a tank to the environment as long as we ask first and have a documented sample and log of quantity drained. Just like a special...