How old is your aunt? When we were growing up my grandparents didn't have running water so we had a bucket that we kept in the kitchen for drinking. We didn't use cups. It had a ladle in it and everybody would fill the ladle, drink from it and return it to the bucket of water. If your aunt is accustomed to doing that it probably has never occurred to her to do differently.

I agree with bridgie that you need to learn to cook.