Let’s just start off with one of the most controversial aspects of this type of cup. Everyone seems to have an opinion on whether or not unlined copper mugs are safe to drink from. But, let’s take the opinion of a professional named Trisha Andrew (an assistant professor at UMass Amherst). As Andrew points out, there is always a chance that a container of any type of material will dissolve slightly into a liquid that comes in contact with its surface. And, in regard to copper, she notes that it is a little faster, but not fast enough to be a concern.
In fact, she calls the notion of being afraid to drink from the material completely absurd. Heck, in order for there to be any issue with acidic pH levels, she also notes, you would have to allow the mug to sit in straight lime juice for a few hours. In short, yes, they are safe.