Water hammer

Water hammer is the banging or knocking sound pipes make when fast-moving water is stopped abruptly — usually by a quick-closing tap, a washing-machine valve or a dishwasher. The moving water slams into the closed valve and sends a shockwave back through the pipe. The odd knock is harmless, but repeated hammering loosens joints and, over years, can crack fittings. Fixes range from simple (fitting shock arrestors, securing loose pipe clips) to a pressure-reducing valve where the building's mains pressure is high — common in newer Dubai towers.