Drain descaling

Drain descaling is the controlled removal of hardened limescale, struvite or rust tubercles that build up inside cast iron, concrete and older clay drains. Engineers use chain flails or milling cutters on flexible drives, or high-pressure rotating jet heads, to bring the pipe back close to its original bore. London's hard water makes scale build-up a common issue in cast iron soil stacks in Victorian conversions across Westminster and Kensington. Descaling improves flow capacity and is often a necessary preparatory step before a CIPP liner is installed, since debris on the host pipe wall prevents the resin from bonding. Operators must protect downstream chambers as descaling can release large volumes of debris that need vacuum tanker recovery.