Pipes Humming or Vibrating

What's happening?

A humming or vibrating pipe is moving water making a part resonate. Unlike a knock when a tap closes, the sound lasts as long as the flow does. The usual suspects are a valve vibrating in the flow, such as a pressure-reducing valve, the float valve of a loft tank refilling, or a tap washer; pressure that is higher than the fittings are happy with; or pipe clips that no longer hold. A hum felt along one run points at the pipe and its fixings. A hum at every tap points at the supply, the stop tap or a valve near the entry. A short bang as a tap shuts is the banging pipes page.

What usually causes it?

• A pressure-reducing valve near the stop tap vibrating or set badly
• Mains pressure too high for the pipework and fittings
• A loft tank float valve that hums while the tank refills
• A partly closed stop tap or isolating valve making the flow turbulent
• Pipe clips that have loosened so the pipe hums against joists or masonry
• A worn tap washer or cartridge vibrating at one tap
• A booster pump or accumulator mounted without anti-vibration fixings

Is it dangerous?

Not by itself. High pressure is hard on fittings and can lead to leaks and bangs over time. The Water Fittings Regulations require fittings to resist pressure surges. A hum that appears after plumbing work should be checked before it loosens a joint.

Can I fix it myself?

Find where it is loudest: at the stop tap, at one tap, or along a run. Open the stop tap fully, then back a quarter turn, because a part-closed valve makes flow noisy. Try running one tap at a time to find a single tap at fault. A pressure gauge on an outside tap tells you whether the supply pressure is high; WaterSafe explains what pressure should be and what to do if it is too high. If the hum is from the loft tank, check the float valve for a worn washer or scale. Re-clip a loose pipe with a rubber-lined clip. Do not adjust a pressure-reducing valve without knowing the setting.

When should you call a plumber?

Call a plumber when the hum is house-wide, when you suspect high pressure or a pressure-reducing valve, when the noise started after plumbing work, when the pipe is hidden in a wall or floor, or when it comes with leaks.

What will the plumber actually do?

• Locate the source by listening along the pipework and testing each outlet in turn
• Measure the static and running pressure with a gauge
• Adjust, service or replace the pressure-reducing valve and fit an expansion vessel or arrestor where needed
• Replace a noisy tap washer, loft tank valve or stop tap
• Clip and cushion loose pipework and anti-vibration mount pumps

Who fixes this

• Leak repair
• Low water pressure fix

What it usually costs

Leaking Pipe Repair Cost

£100–£500 for an emergency burst pipe

Low Water Pressure Pump Cost

£400–£600

Questions people ask

Sources & References

1. WaterSafe: what to do if water pressure is too high
2. WaterSafe: banging noise from my pipework
3. The Water Supply (Water Fittings) Regulations 1999, Schedule 2 (resisting pressure surges)