Leaking drains are a common cause of subsidence where properties are supported on loose or granular materials. Where water escapes from the drain it can soften and/or wash away materials. If structures are supported on ground that has been either softened or washed away in this way it can result in foundation movement and damage to the building structure.
Leaking drains are investigated using CCTV cameras and by testing the strength of the soil adjacent to the leak. Where necessary drains can be repaired by replacement or lining, the bearing strength of the soils improved by treatment and if necessary the strength of the existing foundations improved.