Consuming clean, sweet water in the dream means he will enjoy a clean and happy life provided he does not know its quantity nor is he aware of himself being in a state of tuhr nor does he know himself to be on a journey in a strange, unknown place. The same applies if the water is not sweet. But it the water is brackish and muddy, it means he will suffer from some ailment or disease whose seriousness will depend on how brackish or muddy the water is.