Water Hammer: Causes and Solutions
That hammering you’re hearing in your pipes when you turn off the tap isn’t just annoying. It’s called water hammer, and, left untreated, it can lead to damage to your plumbing system, including weakened joints and leaks, or even burst pipes.
You can save yourself from pricey repairs down the line if you understand what causes water hammer and how to fix it. Our team at Parker Plumbing is here to explain the science behind those banging sounds, the common triggers in your home, and how you can stop it from getting worse.
What Is Water Hammer in Pipes
Water hammer, also called hydraulic shock, happens when water flowing through your pipes suddenly stops or changes direction. Flowing water has momentum, so when the flow gets interrupted, all that energy has to go somewhere. When a valve slams shut, the moving water crashes into it and creates a pressure wave that bounces back through your pipes.
It travels between the closed valve and the next elbow in your piping system, bouncing back and forth until the energy dissipates. All that extra pressure puts stress on your pipes, which can weaken connections over time.
Common Household Triggers
You’ll notice water hammer with some appliances more than others:
- Washing machines
- Dishwashers
- Toilets
- Quick-closing taps
These appliances are common culprits because their electronically operated valves don’t give water time to slow down. The instant stoppage creates the pressure spike that travels through your system.
Why That Banging Sound Occurs
The banging you hear isn’t just the pressure wave itself. When the shockwave travels through your pipes, it makes them vibrate and move. If they aren’t secured well, your pipes will bang against wall studs, floor joists, or other nearby pipes. You might hear a single loud thud or repetitive banging as the shock wave bounces back and forth.
What Causes Water Hammer
Plenty of things can trigger those banging sounds, and often it’s several issues occurring at once.
High Water Pressure
Excessive water pressure is a common cause of water hammer. Most homes operate best between 40 and 60 psi, with anything above 80 psi considered high. If your pressure is approaching 100 psi, water is moving through the pipes so fast that stopping it abruptly will create a pressure shockwave that results in water hammer.
Fast-Closing Valves and Appliances
Solenoid valves in modern appliances stop water flow instantly. Washing machines, dishwashers, and automatic watering systems have these electronically operated components that don’t allow gradual closure.
Loose or Unsupported Pipes
Unsecured pipes magnify the effects of water hammer. If your pipes lack proper support, shockwaves can make them move and bang against walls or joists. Check under floorboards and in ceiling spaces where pipes might have loosened over time.
Worn Stop Valves and Washers
Worn or poorly sealed stop valves can also contribute to water hammer. If the gland packing is loose or the washer inside the valve has deteriorated, pressure changes in the pipes can travel through the valve and cause the internal parts to move or rattle. In some cases, low-quality plastic washers can produce a chattering or rattling sound that is often mistaken for water hammer.
Clogged Air Chambers
Some older systems use vertical pipe segments as shock absorbers. These chambers fill with water or mineral residue over time. Once waterlogged, they lose their cushioning power, and water hammer develops.
Why Water Hammer Shouldn’t Be Ignored
Small bangs might seem harmless, but the damage from water hammer builds over time and can cause big problems for your plumbing system.
Damage to Pipe Joints and Fittings
Repeated pressure waves put stress on your pipe joints and fittings. The vibrations loosen the clips holding pipes in place, and those rattling movements strain connections at every joint. What starts as a minor annoyance can progress to loosened threaded connections and weakened pipe supports throughout your home.
Burst Pipes and Leaks
The hydraulic shock can crack plastic pipes or stress metal components until they fail. Small leaks can lead to hidden water damage, causing mould growth and structural issues. In the worst cases, those pressure surges can cause your pipes to completely burst and flood rooms.
Increased Repair Costs Over Time
The cost of ignoring water hammer is usually much more than the cost of fixing it. Minor leaks reduce water pressure and increase your water usage, which you’ll notice on your bills. You’ll also end up paying for multiple plumber visits rather than addressing the root cause early.
How to Fix Water Hammer
Fixing water hammer usually means starting with the simplest solutions and progressing to more involved repairs.
Secure Loose Pipes
You should check pipes around your house for movement, especially in your ceiling spaces or between walls. Pipe straps or brackets work well where pipes cross joists or studs. Avoid pairing incompatible metals, as some chemically react and corrode over time. If you’re at all unsure, it’s best to leave this kind of work to the professionals and give us a call.
Install Water Hammer Arrestors
These devices use springs and air bladders to absorb pressure surges. You can install them near problem appliances like washing machines or dishwashers.
Lower Your Water Pressure
Household pressure should stay between 40 and 60 psi. A pressure-reducing valve installed on your main line regulates flow throughout your home and protects your whole system.
Replace Worn Valves and Washers
Old valves cause uneven shutoff and contribute to pressure surges. Slow-closing valves stop water hammer at its source and improve plumbing efficiency.
Clear Blocked Air Chambers
You can drain your plumbing system by shutting off the main supply and opening all taps, then refilling slowly. This restores air chambers that have become waterlogged.
Wrap Pipes in Foam Insulation
Foam padding around pipes absorbs inner shock waves and reduces noise from vibration.
Get the Experts in to Fix Your Water Hammer Problems
Water hammer might seem like a minor inconvenience, but ignoring those banging sounds can lead to serious damage and expensive repairs.
Simple solutions might work for some homes, but some cases will need professional attention. Our team at Parker Plumbing helps you protect your pipes before small problems get pricey. Give us a call to stop those banging sounds and keep your plumbing system working at its best.
Dan Parker is the Director of Parker Plumbing and has over 16+ years of experience in the plumbing industry. His commitment to providing exceptional customer service means that he has seen it all – anything to do with residential or commercial plumbing, he knows what to do. Passionate about helping people in his community, Dan strives to offer honest and reliable plumbing services in the Brisbane and Ipswich areas.
