Hi,
I was always taught to use distilled water in my iron. This is especially true if you have hard water.
I don't empty my iron if I'm working on a sewing project. When I used to use my iron for pressing clothes I would empty the iron between uses.
Lately I have to honest that I haven't been careful about either practice. I've been using a B&D with regular tap water. I'll probably more careful with my next iron to use only distilled water.
Have a Great Quilty Day!
Pam M