Nasty mother in law (help!!)

We live with her because our house is currently being remodeled due to a house fire. We buy groceries and she takes it upon herself to drink directly out of the jug. Husband says nothing and I have told him about it several times. He sees no issue with it. I don’t mind it in my own home because I drink off of hubby anyway. But it’s totally different when I buy a drink and his mother is drinking off of it. How should I go about this? I’ve told him to say something multiple times!! It’s to the point I want to buy things and keep them hidden. But then I don’t want to come off as a “bitch”