Why Are My Pipes Banging? A Guide to Solving Water Hammer
Water Hammer - Things That Go Bump In The Night!
Have you ever turned off a tap only to hear a loud thud or a series of violent bangs echoing through your walls? That startling noise isn’t a ghost in the plumbing—it’s a physical phenomenon known as water hammer.
While it might sound like a minor annoyance, those bangs are actually shockwaves that can cause serious damage to your pipework over time. Here is everything you need to know about identifying, fixing, and preventing water hammer in your home.
What Exactly is Water Hammer?
Technically known as hydraulic shock, water hammer occurs when a flow of water is forced to stop or change direction suddenly.
Imagine water rushing through your pipes at high speed. When you shut a valve quickly, that moving mass of water has nowhere to go. It slams into the closed valve, creating a pressure surge that sends a shockwave back through the system. This causes the pipes to vibrate or strike against the wooden joists in your floor or walls, resulting in that signature "hammering" sound.
Common Culprits:
- Fast-acting valves: Quarter-turn taps, washing machines, and dishwashers shut off almost instantly, which frequently triggers the noise.
- High water pressure: If your home’s mains pressure is too high, the force of the "stop" is much more violent.
- Loose pipe clips: If the brackets holding your pipes to the joists have loosened, even a small pressure change will cause the pipes to rattle.
Is Water Hammer Dangerous?
In short: Yes. While your pipes won't explode instantly, the repeated stress of hydraulic shock can lead to:
- Leaking Joints: The constant vibration weakens soldered joints and threaded connections.
- Pump Failure: The shockwaves can travel back to your boiler or secondary pumps, damaging internal components.
- Burst Pipes: In extreme cases, a particularly strong surge can rupture a weakened pipe, leading to significant water damage.
How to Fix Water Hammer: 3 DIY Steps to Try
Before calling out a professional, there are a few things you can try to quiet the noise.
1. Check Your Water Pressure
The most common cause of water hammer is high water pressure. Use a pressure gauge (available at most DIY stores) to check your taps.
- The Target: Your home's water pressure should ideally be between 2.0 and 3.0 bar.
- The Fix: If it’s higher than 4.0 bar, you may need a Pressure Reducing Valve (PRV) installed on your main water line.
2. Secure Loose Pipework
If you can access the noisy pipes (perhaps under the kitchen sink or in a crawlspace), check the clips. If a pipe is loose, it will "jump" when a tap is turned off. Installing a few extra plastic pipe clips or wrapping the pipe in foam insulation can often dampen the noise entirely.
3. Replenish Your "Air Chambers"
Older plumbing systems often have vertical lengths of pipe near valves called "air chambers." These act as cushions. Over time, these can fill with water and lose their cushioning effect.
To fix this: Turn off your main water supply, open the highest tap in the house, and then drain the entire system from the lowest tap. Once empty, turn the water back on. This traps a fresh pocket of air in those vertical pipes, restoring the "cushion."
When to Call Assett Plumbing
If you’ve tried the steps above and your pipes are still thumping, you likely need a professional solution. We can install Water Hammer Arrestors - small, spring-loaded cylinders that absorb shockwaves before they reach your pipework, or adjust your internal pressure settings safely.
Local Expert Plumber Tip: "Don't ignore a bang. A £50 fix today can prevent a £5,000 floor repair tomorrow due to a burst pipe hidden behind your walls."
Need a Hand?
Assett Plumbing provides expert leak detection and pipe repairs across Northampton, Kettering, Corby, and Wellingborough.
Would you like me to book a pressure check for your home or provide a quote for installing a water hammer arrestor?
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