How to Fix the Water Hammer Problem in Your Plumbing

photo: Pixabay

Water hammer is the most common home plumbing problem that can be recognized as a pounding, banging, or thumping noise followed by pipe vibration. While it is quite annoying, this can also be a serious problem affecting your water heater's performance and safety.

In order to properly deal with this issue, check out this troubleshooting guide and learn about causes, symptoms, and how to prevent and get rid of water hammer fast and easy.

Is the water hammer a big problem and can it be fixed?

What causes water hammer?

Water hammer happens when you quickly close the tap or valve, so moving water inside the plumbing suddenly stops.

Due to sudden pressure changes and shock waves, pipes will usually hit against the house's framing, creating a banging or thumping noise.

As the water movement stops abruptly, a high-intensity pressure wave is created, traveling back and forth between the point of relief and the point where the stop is until it dissipates in the plumbing system.

Note: No matter whether you live in a new or old house, water hammer can happen anywhere and anytime.

The problem is not only with the banging and irritating noise but its destructive nature for plumbing, fittings, and your heating unit. The pressure created in plumbing can go over 60 times.

For other water heater noise-related issues, check out this repair guide.

As mentioned before, excessive pressure builds up in the plumbing system and goes from the pipeline into the tank, where permanent deformation might occur. Usually, the tank shell will expand, and by measuring the circumference at various locations along with the tank, you can see how serious it is.

High pressure in the heating system and pipes banging against the framing members can cause an unstable plumbing system when the water hammer occurs.

For example, the flue tube installed on a gas water heater on one side and through the wall on the other might collapse. With the deformed vent, flue gases won't be able to find their way out, causing the flame and gas combustion to spill out from the combustion chamber.

Water hammer arrestor: Repair and prevention tips

Water hammer arrestor
(photo: amazon)

The solution for the problem is to install a water hammer arrestor (which might be required by the local code), such as this Sharkbite or this model from Watts.

The element is also known as the air chamber, and it is designed to work similarly to expansion tanks, with a diaphragm that separates an air chamber from the water in the plumbing system. The air works as a cushion, absorbing the shock wave from the excessive pressure.

You should identify the source of the shock wave so you can install the arrestor close to that point.

Installation tips

As explained, the water hammer arrestor should be installed close to the appliance, fixture, or fittings that is causing the issue. The installation is as simple as installing any of the fittings. When dealing with copper pipes, you can either solder to the pipe or buy a water heater arrestor with compression fittings.

Other ways to prevent water hammer

While the arrestor installation is one of the most effective ways to prevent water hammer, there are also other methods.

In order to avoid water from hitting the valve mechanism and creating pressure and vibrations, you can use a check valve with a spring that silently moves into the closing position.

Another solution is to install an expansion tank or pressure-only relief valve that works as a sacrificial valve when dealing with abnormal pressures.

Flushing the water heating system, replacing worn stop valves, and fixing the loose pipes are also ideas that can help you fix the problem.

Why my water heater is making a noise?

A common question from consumers is: My water heater makes a popping noise? Is that water hammer, noisy pipes, or something else?

Plumbing is not always "guilty" of all kinds of noises you can hear when running a heater, washing machine, or dishwasher.

The rattling sound might come from a defective seat washer, even when the tap is barely open.

Moaning or chattering sounds may be caused by high pressure.

A ticking noise occurs when you open a hot tap, and hot water suddenly runs through the cool hot water pipe. It might also be that a copper pipe expands due to high water temperature.

The common cause of ticking noise and water hammer is if your sink or shower/tub is using a single lever faucet or due to the dishwasher and washing machines' automatic solenoid valves. Sometimes a simple change of a defective seat washer is the solution. More info about water heater noise can be found here.

Conclusion

There are several approaches to preventing and repairing the water hammer problem, where noise and vibration are the main issues that have to be eliminated. Designing the plumbing pipes properly and replacing the undersized pipes with larger ones are the way to go if possible. For the existing plumbing system, wrapping the insulation around the pipes might be sufficient to minimize the rattling noise, also securing the loose ones. Or simply install a water hammer arrestor.

This is a fairly simple DIY project.

Note: If there is damage to a tank heater due to a water hammer issue, the manufacturer is not eligible for warranty compensation.