Inspired by a helpful YouTube guide. We based this walk-through on the Plumberparts video "Curing water hammer! Banging pipes!", a well-regarded UK plumbing channel with over 130,000 subscribers. It covers the causes clearly and is worth watching alongside this guide - the section on air chambers is particularly useful.
1. Work out what is triggering the bang
Before reaching for anything, spend a few minutes listening. Does the bang happen when you turn off a tap quickly? When the washing machine finishes filling? When the toilet cistern stops? Knowing exactly when it occurs tells you where to look.
Water hammer is caused by water in motion stopping suddenly - the momentum has to go somewhere, and it goes into the pipes. Fast-closing solenoid valves on washing machines and dishwashers are a very common culprit in UK homes.
2. Check the mains water pressure
High pressure makes everything worse. Fit a pressure gauge to an outside tap or use a gauge at the mains stopcock - normal UK household pressure is 1 to 3 bar. Anything above 3 bar and you will want a pressure reducing valve fitted at the incoming supply.
That is a job for a plumber, but it often sorts hammer that nothing else will touch.
3. Secure any loose pipes
Pipes that are not clipped properly can bang against joists and plaster when water moves through them quickly. Go round the accessible pipework - under the kitchen sink, in the airing cupboard, along skirting - and add pipe clips or slip foam lagging over any sections that are free to rattle.
This alone cures a good proportion of cases, particularly in older Kent houses where pipes have worked loose over the years.
4. Replace worn tap washers or float valves
A worn washer in a tap can cause a type of water hammer called "water singing" - a vibrating noise rather than a bang. Replacing the washer costs almost nothing and takes 20 minutes.
A faulty float valve in the toilet cistern or cold water tank can also chatter as it closes. Replacing the valve or fitting a delayed-action valve (which closes slowly) usually sorts it.
5. Fit a water hammer arrestor
An arrestor is a small device fitted to the supply pipe near the offending appliance. It contains a piston and air chamber that absorbs the pressure shock when a valve snaps shut. You can fit them yourself on accessible pipework - they push straight onto standard 15mm compression fittings.
For washing machines and dishwashers, fit one on the hot and cold inlets. They are available from any plumbers' merchant and most large DIY sheds.
6. Drain and refill the system to restore air chambers
Older plumbing systems used air chambers - short sections of capped vertical pipe - to cushion water hammer. Over time these fill with water and lose their cushioning effect. Draining the system fully allows air back into the chambers.
Turn off the mains stopcock, open all the taps in the house to drain the pipes, then close them and turn the water back on. It sounds too simple, but it genuinely works on older installations where air chambers are built in.
When to call a handyman
Call Richard if the banging persists after you have tried the above, if the pressure is consistently over 3 bar and needs a reducing valve fitted, or if you suspect the source is buried in the wall or under the floor. Some hammer is deep in the system and needs a proper diagnosis before you start opening up walls.
Need help with noisy pipes?
The Sandwich Handyman can track down the cause of water hammer, secure loose pipework, and fit arrestors or delayed-action valves across Sandwich, Deal, and the surrounding East Kent villages.
Contact Richard