In England, local accents can vary considerably over quite a short distance. It can be difficult for someone who is not from the area to understand everything which is being said.

Of course it works both ways. I'm sure the waitress would have had a similar experience had she asked for a "glass of woah'ah" in a restaurant in the US - except of course that she would not have to, as one would have been offered as soon as she sat down. That is not usual in UK restaurants. Here, if you want water you'd usually be expected to buy an expensive bottle of mineral water.

When I first travelled in the US, I was initially confused to be offered a bowl of green salad as a starter - here it would usually be served as a side dish with a main course. I caused considerable confusion myself by asking for Lea & Perrins (I knew better than to ask for Worcester Sauce) to put in my glass of tomato juice - the waiter went to ask the head waiter, and they both watched from a distance with a mixture of horror and curiosity as I added it to my drink.