Plumbing notes · any time

Thumps, rattles and whistles in the walls

Noisy plumbing is irritating and occasionally a warning. The kind of noise points to the cause.

A red and blue fire hydrant sitting in the middle of a forest — From the almanac guide on washing machine hoses.

A thump as a tap snaps shut

That is water hammer: a moving column of water stopped dead. High pressure and loose pipe make it worse. Arrestors near fast-closing valves and a reducing valve calm it.

Rattling

Loose hangers let pipes shift. Proper clips usually silence them.

Whistling or squealing

Worn washers, half-closed stops or high pressure
Tired toilet fill valves
Faucet cartridges caked with minerals

One more thing

Washing machines and dishwashers are frequent hammer culprits because their solenoid valves close almost instantly. If the bang happens only when one of those appliances finishes filling, an arrestor on that supply line usually solves it.

Older homes sometimes had air chambers built into the plumbing near fixtures: short vertical capped pipes that cushioned the shock. Over years they waterlog and lose their cushion. Emptying the house plumbing can restore them temporarily, but modern arrestors are a more permanent fix.

If pipes creak or tick as hot water flows, that is usually thermal expansion as copper warms and slides against a hanger or a joist. Plastic isolators between pipe and support quiet it down.

If a noise is new and sudden, take it seriously. A pipe that starts knocking after years of silence may have lost a hanger or developed a pressure problem, both easier to fix before something lets go. Note when it happens and which fixture is involved before you ring.