Water Hammer Arrestor Installation
Every time a washing machine valve closes, it sends a shock wave back through the pipes. You hear it as a single loud bang, usually right when the machine finishes filling. What you do not hear is what happens next: the shock travels through the whole system, loosening joints, stressing fixture connections, and wearing out valves in other parts of the house. Over years, that adds up. A water hammer arrestor absorbs the shock before it travels. It is a small, inexpensive part that installs in line with the washer supply, and it is worth adding any time the washer is being serviced or replaced. We install arrestors on both hot and cold lines when possible, because water hammer can come from either side.
Common problems
- Loud banging when washer fills
- Pipes rattle when water shuts off
- Joints loosening over time
- Fixtures wearing out faster than expected
- Washer valve failure
- Pressure shock in nearby fixtures
- Repeated pipe noise in the same spot
What we do
- Diagnose the source of the water hammer
- Install arrestors on hot and cold lines
- Replace existing arrestors
- Check supply line pressure
- Inspect nearby joints and fixtures
- Test the system after installation
- Advise on pressure if it is unusually high
Services & pricing
Water Hammer Arrestor — Add or Replacement (parts included) — $189
All prices are flat rates for standard residential conditions. The $89 call-out fee is added to whichever service you approve.
FAQ
What is water hammer, exactly?
Water hammer is the shock wave that travels through a pipe when a valve closes quickly. Water is not compressible, so when the flow stops suddenly, the energy has to go somewhere. It goes back through the pipe as a pressure spike. You hear it as a bang, but the pressure spike itself is what does the damage.
Can water hammer damage my pipes?
Over time, yes. Each shock loosens joints slightly. It also stresses fixture connections, shut-off valves, and appliance valves throughout the house. Most homes do not fail suddenly from water hammer, but the cumulative damage shows up as leaks and failures in places that seem unrelated to the laundry room.
Do I need one arrestor or two?
Ideally two — one on the hot line and one on the cold. Water hammer can come from either side, and the shock from the hot line can be just as strong as the cold. If only one arrestor is being installed, we usually put it on the cold line first, since that valve tends to close faster.
Can I install a water hammer arrestor myself?
You can, but it has to go in the right place, and the connection has to be tight enough to hold constant pressure. If the arrestor is installed too far from the valve, it does not absorb the shock effectively. If the connection leaks, it leaks behind the washer where you cannot see it.
How long does installation take?
A standard arrestor installation is usually under an hour. If two arrestors are being installed, or if the shut-off valves also need to be replaced while we are there, it takes a bit longer.
CTA
Hearing a bang when the washer fills? Call or text (778) 683-3344 and describe what it sounds like. We will tell you what it usually costs to fix.