First off, you should have rang the doorbell to see if some one was home if you needed water . Then explain your situation and ask permission to borrow water. If they are not all that friendly, knock 5 bucks off their application.
I think the customer was a "dick", but she may have experienced "shock & awe" >> Like when she gets her repair bill from her Lexus dealer
Bottom line: always respect one's property. By asking permission and explaining your situation, you may have gained her respect & empathized with you. But if she refused to let you borrow water, dump her like a hot potato.