There is no harm in making cups with stainless steel. This kind of cup usually has good fall resistance and safety, and the heat preservation effect is usually good, so we have no problem drinking water with this kind of cup.
However, it should be noted that it is best not to use stainless steel cups for coffee, juice, carbonated drinks, etc. In order to prevent some substances in stainless steel from precipitating from these drinks and causing harm to the body.
At the same time, when we buy stainless steel cups, we should choose the cups produced by regular manufacturers, and we can't clean them with bleaching powder and soda, because these things may react with the substances in stainless steel.