Three-dimensional topologically connected watercourse network of Great Britain. The data represents the approximate central alignment of watercourses and includes inland rivers, tidal water, lakes and canals attributed with watercourse name, flow direction, gradient, primary flow, TOID reference, EA or SEPA catchment name and ID. Polygons and lines representing the water area and its banks are not included (those are part of OS MasterMap Topography layer). OS MM Water Network is based on the INSPIRE Hydrography Data Specifications. The OS MasterMap Water Network, as currently published, consist of topologically structured link and node network.