And during supper Jesus, knowing that the Father had given all things into his hands, and that he had come from God and was going to God, got up from the table, took off his outer robe, and tied a towel around himself. Then he poured water into a basin and began to wash the disciples' feet and to wipe them with the towel that was tied around him. (John 13.3-5)
Jesus uses water as an effective and surprising channel to demonstrate the central aspect of his vision for the disciples' ministry. According to John's gospel the Last Supper took place in an undisclosed and secret room, in order for Jesus to be alone with his disciples and loved ones. There were no slaves or helpers to break the bread or to pour the wine - just the gathered few.