Banging pipes and dripping taps — do I need a pressure-reducing valve for high mains pressure?
A few plumbing niggles that might be connected: my pipes bang/hammer when a tap or the washing machine shuts off, some taps drip, and appliances (heater, mixers) seem to wear out fast. Someone suggested the mains water pressure is too high and I might need a pressure-reducing valve (PRV).
- How do I know if my pressure's genuinely too high?
- What are the symptoms — is the banging really pressure-related?
- Does a PRV actually fix it, and where does it go?
Trying to understand whether this is one root cause (high pressure) behind several annoyances before I call someone. Is a PRV the answer, or am I chasing the wrong thing?
3 answers
Short answer: banging pipes, dripping taps and appliances failing early are classic symptoms of mains pressure that's too high — and a pressure-reducing valve (PRV) is exactly the fix. It's a valve fitted on the incoming main that caps the pressure entering your home to a safe, steady level (commonly set around 3 bar). One PRV can quietly cure several problems you're treating separately.
How to know it's high pressure: - Water hammer — the banging/knocking when a tap or appliance valve shuts suddenly. High pressure makes the shockwave worse. - Dripping taps & running toilets — seals and washers can't hold back excessive pressure, so they weep and fail early. - Short appliance life — water heaters, washing-machine and dishwasher inlet valves, and flexible hoses all suffer and fail sooner under high pressure. (This is also why over-pressure bursts those flexi hoses that flood a cupboard.) - Spitting/forceful taps and relief valves weeping. - The real proof: a plumber puts a pressure gauge on a tap. Much above ~4–5 bar and it's worth reducing; a PRV is typically set around 3 bar.
What a PRV does and where it goes: it's fitted on the incoming mains (where the supply enters the property) and holds the downstream pressure at the set level regardless of what the mains does — high floors and areas with strong mains pressure benefit most. Set-and-forget once it's in (though the valve itself should be checked periodically).
So you're likely not chasing three separate faults — you may have one cause (high pressure) behind the hammer, the drips and the appliance wear. Get a licensed plumber to gauge the pressure and fit a PRV if it's high. Anyone fitted one and had the banging just… stop?
Fitted a PRV after exactly these symptoms — the water hammer was driving us mad and taps kept dripping no matter how many washers we changed. Plumber gauged it, pressure was way up, put a PRV on the incoming main set to around 3 bar, and the banging stopped and the drips settled. The bit that convinced me it was worth it: we'd been replacing tap washers and a heater part like it was normal, and it wasn't normal, it was the pressure quietly wrecking things. One valve sorted several problems.
Worth getting the pressure actually measured rather than assuming — mine felt strong but was within range, and my "water hammer" was more about a loose pipe that needed clipping plus needing an arrestor, not whole-house pressure. So a gauge reading first tells you whether it's a PRV job or something more local. But if the pressure genuinely is high, everyone I know who fitted a PRV said the same thing: several little annoyances disappeared at once.
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