Although the larger streams are usually all right to drink from, you should carry a water bottle at all times, as your throat will become dry and you'll soon become thirsty. You shouldn't drink from smaller brooks, especially in summer when the cows are on higher pastures. Pack a lunch! Restaurants are few and expensive in the mountains. Buy some bread, cheese, sausage, and fruit at the nearest grocery store and enjoy a feast in the world's biggest outdoor cafe.