John 4:11

The woman said unto him, Sir, thou hast nothing to draw with, and the well is deep: whence then hast thou that living water?

The woman's response shows that she did not understand what was meant by "living water," hence the question of its source, especially in view of the fact that Jesus had no rope.

Whence then hast thou that living water ... indicates that the woman had already apprehended the fact that Jesus was not talking about the water of Jacob's well. This question of hers reveals that she understood at least a part of what Jesus was saying to her, and that she might have suspected, even at that point, the metaphorical significance of his words, as the next verse shows.