Instead, the water that I will give to him will become in him a fountain of water, springing up into eternal life.
Other versions
King James Version
But whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life.English Standard Version
but whoever drinks of the water that I will give him will never be thirsty forever. The water that I will give him will become in him a spring of water welling up to eternal life."New International Version
but whoever drinks the water I give him will never thirst. Indeed, the water I give him will become in him a spring of water welling up to eternal life."