The expanding stopper (10), for controlling flow of liquid through a conduit (1), comprises an expandable bag (2) having elastic end portions (5,6). Inlet and outlets (7) are provided for a fluid under pressure being hermetically connected through the upper part of the bag and adapted for connection to a distribution system (9) for the fluid. The inlet and outlets are provided with connections (8) for the attachment of the bag to a part of the conduit. The latter may form part of a ground water control system, such as a drainage or irrigation system.
展开▼