This national digital GIS product produced by the British Geological Survey indicates the susceptibility of corroded underground ferrous (iron) assets (e.g. pipes) to failure, as a result of ground instability. It is largely derived from the digital geological map and expert knowledge. The GIS dataset contains eight fields. The first field is a summary map that gives an overview of where corroded ferrous assets may fail. The other seven fields indicate the properties of the ground with respect to corrosivity and hazards associated with soluble rocks, landslides, compressible ground, collapsible ground, swelling clays and running sands. The data is useful to asset managers in water companies, local authorities and utility companies who would like to understand where underground ferrous assets are susceptible to failure as a result of ground conditions.