What Causes Noisy Water Pipes?
Banging, humming and whistling pipes each point at a different fault.
Banging: water hammer
A thud when a tap or washing machine valve closes is water slamming to a stop. Modern quarter-turn valves make it worse. Water hammer arrestors or a pressure check usually cure it, and loose pipe clips amplify it.
Humming or vibration
A constant hum often means mains pressure running too high for the pipework, or a pump bearing on its way out. A pressure-reducing valve set correctly quiets the whole house.
Whistling and kettling
A whistling tap is a worn washer or restricted valve. A boiler that rumbles like a kettle has scale on its heat exchanger, and that one shortens boiler life, so treat kettling as a service light, not a quirk.
Water hammer
A bang when a tap or an appliance valve closes is water hammer: the moving column of water stops abruptly and the shock travels through the pipework. Washing machines and dishwashers with fast solenoid valves are the usual trigger. The fix is an arrestor near the offending valve, plus properly clipped pipework, the noise is the pipe moving, and a pipe that moves eventually leaks.
Humming, whistling and ticking
A hum that rises with flow is usually a partly closed valve or a worn washer vibrating. A whistle at one tap is nearly always that tap's cartridge. Ticking as the heating warms is pipework expanding against a joist or a clip, which is harmless but easily fixed with felt at the contact point during any other job.
Kettling, and why it matters in London
A boiler that sounds like a kettle coming to the boil has scale on the heat exchanger restricting flow, so water flashes to steam against the hot surface. In hard-water London it is one of the most common heating noises we are called about. It is not cosmetic, sustained kettling overheats the exchanger and shortens the life of the boiler considerably.
The cheap jobs in October that prevent the expensive ones in January.
Higher bills, warm floor patches, a meter that ticks overnight, how leaks announce themselves.
A spitting, coughing tap after plumbing work is usually trapped air. Two fixes cost nothing.