Water Line Repair & Replacement
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Plumbing guide
Water Hammer Noise in Goodyear, AZ Homes: What to Do
When a valve closes quickly, moving water slams to a stop and the pipes bang. The noise is annoying, and repeated shocks can loosen fittings.
By the Goodyear Express Plumbing team ·
What causes the bang
Water has weight and momentum. A washing machine valve or a quick closing faucet stops it suddenly, and the shock travels through the pipes. If lines are loose in their straps, they knock against framing.
High pressure makes it worse, and so does a lack of air cushion in the lines.
Where it shows up
Washing machines, dishwashers and ice makers have fast solenoid valves, so they are common culprits. Single handle faucets can also cause it. Note which fixture triggers the sound and whether it is hot or cold.
The sound may come from far away in the house, so listen closely.
Air chambers and arrestors
Older homes used a short vertical pipe called an air chamber to cushion shocks. Over time it fills with water and stops working. Draining the system by closing the main and opening taps can refill it with air.
A water hammer arrestor is a sealed device with a piston or bladder that absorbs shock. Plumbers install them at fixtures that cause trouble.
Cause, symptom and fix
Line up your symptom with the cause.
| Cause | Symptom | Remedy |
|---|---|---|
| Waterlogged air chamber | Bang when a valve closes | Drain and recharge the chamber |
| Excess pressure | Loud hammer and leaks | Test and replace the regulator |
| Loose straps | Knocking inside walls or attic | Add supports |
| Quick-closing valve | Thump after the washer stops | Fit an arrestor |
Pressure and regulators
Pressure above a moderate range increases the force of the shock. A gauge on a hose bib shows the number. If it is high, a failing regulator may be the cause. Read about low pressure in the water line repair options if the supply line is involved.
Replacing a regulator is a routine job.
Loose pipes and supports
Pipes in attics and walls need straps spaced correctly. If they have come loose, they rattle and bang. A plumber can add supports where the pipe is accessible.
Foam insulation around pipes also reduces noise.
Why not ignore it
Repeated hammer can weaken joints, damage valves and shorten the life of appliances. It can also loosen a connection that later leaks. Fixing the cause early costs far less than repairing water damage; see water damage restoration.
When to call
Call if the bang is loud, if it happens throughout the house, or if you see a new leak. Tell the dispatcher which fixtures trigger it and what the pressure reading was.
A simple way to find the source
Close the main, open every faucet and let the lines drain. Close the faucets, then open the main slowly. Now run one fixture at a time and listen. The fixture that bangs is the one to fix. Hot and cold can behave differently, so test each.
If the whole house knocks regardless of the fixture, suspect high pressure or loose straps rather than one valve.
Fixes by cost and effort
The cheapest step is to refill the air chambers, which takes minutes. Next is adding foam pipe supports where lines rattle. Installing a hammer arrestor at a washing machine or dishwasher is a modest job. Replacing a pressure regulator takes longer but fixes the root cause when pressure is high.
Ask the plumber to test pressure first, so they do not install devices that mask a regulator problem.
Noise that is not water hammer
Not all pipe noise is hammer. A steady squeal can be a worn valve or a partly closed stop. A ticking sound when hot water runs is usually pipes expanding. A rumble in the heater is sediment. Describing the sound and when it happens helps a plumber tell them apart on the phone.
See water heater repair for rumbling and popping from the tank.
Why Valley homes can be prone
Homes in the Valley often have high static pressure because of the way the system is supplied, and many use PEX or copper that runs through hot attics. Thermal expansion adds stress where lines are strapped tightly. Both factors make a well set regulator and loose, cushioned supports a good idea.
If your home was built long ago, ask the plumber to inspect valves and the regulator during a visit.
Appliance specific tips
Washing machines and dishwashers often cause the loudest knocks. Check that their supply hoses are not kinked and that the shutoff valves open fully. Some machines have arrestors built into the hose; replacing a worn hose can help.
Ice maker lines can also cause a short knock. A small arrestor on the line fixes it.
Follow up after a fix
After you refill chambers or add arrestors, run the loudest fixtures and listen over a week. Hammer that returns means the chambers are filling again, and a permanent arrestor is a better answer. Write down the dates.
If pressure was high and you replaced the regulator, recheck the gauge a few days later.
Long term care
Check the regulator every few years, and exercise shutoff valves. Replace worn washing machine hoses on schedule. Add pipe supports when you renovate. Keep a short log of pressure readings after changes in the neighborhood.
These steps cost little and reduce the stress on joints, valves and appliances.
When hammer points to a leak
Banging that began after a repair, or that comes with a pressure drop and a spinning meter, can indicate a loose joint or a hidden leak. Run the meter test described in our leak detection page. A change in sound is information.
Do not wait on a loud bang
A hammer strong enough to shake the wall can crack a fitting or loosen a supply line. If you hear it, close the fixture's stop valve for the appliance involved and call. Replacing a supply hose or adding an arrestor is quick, while a burst joint behind a wall is not. Early action keeps the repair small.
Common questions
Water hammer questions
Mild hammer is a nuisance. Strong repeated shocks can damage fittings.
If air chambers are waterlogged, yes. It is a temporary fix in many homes.
Most are sealed. If one fails, replace it.
Yes. Check pressure with a gauge.
Related services
Repiping & Whole-Home Pipe Replacement
Replace tired supply piping throughout the home once spot fixes stop working.
Faucet & Sink Repair
Cure drips, weak flow, stuck stop valves and puddles in the cabinet below.
More plumbing guides
Low water pressure: causes and checks
A weak stream at one tap and a weak stream at all of them have different explanations.
PEX vs copper pipe
Two common supply pipes compared, with questions worth asking before a repipe.
Water heater leaking from the bottom
Water beneath the tank may be a fitting or the tank itself. Sort out which, and what to do first.
Pipes banging at night?
Phone in and describe the sound. The dispatcher will find a contractor nearby.