The features of water users in the public network are analyzed from the aspects of water-supply method, water right registration, water fee source and water monitoring. The water right registration is the precondition for water amounts of contract water-saving management of public network. The water trading modes of “Water-saving before transaction” and “Payment before water-saving” are proposed. They both include direct sale and commission sale according to the participation of water-supply corporations. The affirmation and transaction of amounts for contract water-saving management are identified as the key elements for trading regulation and risk control. The third-party evaluation mechanism and water trading feasibility demonstration are the effective measures to reduce risks and to avoid negative externality of water trading.