Bests & Worsts Reviews from Amazon

5 months after purchase this product, I found that inner lid around screws area is getting rusty. I contacted Zojirushi and I was told that this is the accumulated materials from water... the company will not respond for replacement. However, the fact is that the inner container that directly interacts with water is really clean, whereas the inner lid actually not contacts with water directly. I think this is the problem with the material used in the inner lid. I am really disappointed about the Zojirushi's response.