Contemplation on the Man Bearing the Pitcher of Water

Question: In the Gospel, who is the man in the city bearing a pitcher of water? Why water, and why are the disciples told that they’ll meet him and are to follow him? Who’s the master of the house? Why don’t the Gospel writers mention his name? What is the large upper room where a table’s been laid and in which the dread mystery of the Last Supper takes place?