the living water

Commenting on Jesus' encounter with the Samaritan woman and the contrast between the water from the well that Jacob gave to his family and the living water that Jesus offers, Ridderbos very helpfully comments,

the point of this story and the way by which Jesus leads the woman to faith can only be understood against the salvation-historical background of God's revelation to Israel. The gift of water from the well of Jacob was for the Samaritans, like the manna in the wilderness to Israel, a reminder of the sacred tradition - continuing evidence of God's richly salvific involvement with his people through history. When Jesus describes the gift of God in terms from tradition, such as 'living water' and 'bread from heaven', the adjectives 'living', 'true', 'good' and the like are rooted theologically not in an ontological contrast between illusion and reality but in a salvation-historical contrast. What Jesus brings is the fulfilment, the 'truth' and the 'fulness' of the gift of God. Everything that preceded had reference to that fulness, but could not provide it.

(Herman Ridderbos, The Gospel of John: A Theological Commentary, p.157)