6 causes for water hammer in washing machines & toilets

Do you hear some banging noises in your pipes every time you close a valve? It could be a sign of a serious phenomenon known as a water hammer. Protect your pipes from this catastrophe by informing yourself of all the causes and prevention methods below. Here are 6 causes of water hammer in pipes, washing machines, and toilets, and their best solutions.


The most common causes for water hammer in pipes, washing machines, & toilets are air pockets and old pipes. Pressure problems are common in older homes with pipes made of materials that would rust over time. The best solution to get rid of the water hammer is by using a water hammer arrestor.

What is a water hammer?

A water hammer is a phenomenon that causes the utmost stress on your piping system. It occurs when flowing water is suddenly stopped and forced to move in the opposite direction due to closing a valve. It is why it’s more likely to occur in a valve-operated piping system. A major sign of this phenomenon is its noise in banging form.

When it happens, the pressure is raised five to ten times more than the usual capacity of the water system. It causes extreme stress on the pipes and can even cause bursting.

water hammer arrester

Causes for water hammer in washing machines & toilets

Here are some probable causes for water hammer in the washing machine & toilet.

1. Air pockets

Shockwaves through the pipes are what cause this. Especially if you’ve got a high-pressure system, you can expect air to accumulate fast since it travels more speedily than water. Air pockets can cause banging noises and water sputtering when you open the tap, shower, or sprinkler.

2. Abrupt opening and closing of valves

Since fill valves in toilets and showers close suddenly when the intake is complete, it causes pressure to be created and thus makes the pipes shudder. It is more severe in fast-acting solenoid valves that close faster than standard valves. Fast-acting pressure will accumulate and create loud noises and burst pipes if not handled in time.

3. Unsuitable taps

water hammer arresters

Some specific fittings can cause damage more quickly than others. It is the case with mixer taps, for instance. Install taps with soft-close valves that do not create stress in the pipes. Also, take care to install fill valves in toilet tanks that have appropriate valves.

4. Old pipelines

Does your home have pipelines from the ’80s? If everything in there is creaking and croaking like a grandma, the pipes are likely too. Pipes can rust, burst or break over time with pressure. Before the 60s, houses were made with iron pipes that were covered with a layer of zinc. Zinc erodes over time and causes rusting as well as breakage. That’s why Pressure problems like a hammer are common with old houses.

5. Very high water pressure

It can be tempting to have great water pressure in the shower. It’s a feature that sells houses faster. But too much pressure can lead to pipes breaking, pumps failing, and damages worth thousands of dollars. Check and maintain adequate pressure in the pipelines, especially if you notice thumping sounds.

6. Bad repairs

There are plenty of repairs that a home goes through, especially in plumbing. If somebody has done a bad job with valves and fittings, it can reflect in the form of these ferocious noises. If you’ve had work done recently and suspect it might have made things worse, call a professional to help you out.

It happens after a toilet flushes

water hammer arrester out of the box

Your toilet fill valve has the job of refilling the tank every time it’s flushed. But it has to close sometime. When it suddenly cuts off the water supply after the tank is full, the water is forced to move in the opposite direction. It creates a surge of pressure. It causes a loud banging noise in your pipes.

Although it may seem like something that can be ignored and haunts you the whole day, it can cause problems in your pipes and your toilet.

It can also be caused if your fill valve doesn’t close completely. Either way, installing a water hammer arrester is the best way to prevent burst pipes. We show you how to do this a little below.

What does it sound like?

If you’ve ever heard a jackhammer, that’s almost what it sounds like. Suppose you’re turning off your shower or any tap and hearing loud hammering noises. That’s it. The hammering noises are like loud bangs that are impossible to miss. It is a major sign that the pipes need extra maintenance to avoid a disaster.

It happens when the sprinkler system turns on

Sprinkler systems are trickier than other pipe fittings. Air is already less dense than water and travels at a higher speed. In sprinkler systems, the water is likely to stop and go more frequently than in other fittings abruptly.

Once this happens, hammering is likely to occur in the pipes. One of the ways you can do this is by letting the air bleed out first. Open up the furthest head on the line first to let the air out. Trapping air is prevented, and thus the likelihood of pressure surge is avoided.

Water hammer effects

2 Water Hammer Arresters

Over time, this phenomenon will likely result in big damages if not taken care of. The damage can be done overnight or over a longer period which goes unnoticed at first until it’s harmed.

Here are some things you can watch out for:


The pressure surge of five to ten times is unprecedented in a system. Instead of having a full-blown bursting pipe, it’s likely that you can experience leakages from valves and joints. Smaller leaks will go unnoticed until they turn big. Check for wetness around the pipes, the back of the toilet tank, and other joints.

Pump damage

Leaks are visible damage, but sometimes the damage is done on the inside where it’s unknown to you. Pumps, valves, welded joints, and fittings can be permanently damaged with the pressure burst from water hammers.

For instance, the pump inside the toilet tank can be affected and thus prevent flushing in the toilet and causing a lot of discomfort for family members and guests.

Burst pipes

Pipes bursting are one of the most likely occurrences in this scenario. Not only is it scary, but also very difficult and expensive to repair. It can lead to the failure of other connected systems as well.

Replacement of one pipe will lead to the replacement of the nearby fittings since they would have been affected too. Until the work is done, you and your family won’t be allowed to use the water supply line. It is a major inconvenience.

Failing of other appliances

When a pipe bursts or leakage occurs, the damage can be more than just to fittings. It can extend over to other appliances sitting nearby. For instance, water hammers in the dryer and washer’s fittings can damage your laundry appliances. A pipe bursts near light fittings or open sockets, and you could even have an electrical fire on your hands.

Here is a simple way to get rid of the water hammer.

How to fix and get rid of a water hammer

  1. Shut off the main valve.

    Shut off the main line connection to your home. It will be a valve in your main line next to the meter. Your realtor must have introduced it when he showed you the house.

  2. Open up taps.

    Open up all the taps, shower, and other fittings to drain the excess water.

  3. Close the taps.

    Close all the faucets and ensure they are tightly cut off from the flow.

  4. Turn on the water.

    Now you can turn on the main valve line. Let the water flow back to the pipes. What you have done is release the air chamber of waterlogging. It will fill it with air again. The air cushions the pressure experienced during the valve’s closing.

Best models

There is a simpler way to keep the pipes under check. You can simply install a water arrestor. Arrestors are small cylinders filled with air that cushion the effect of a quick shut-off valve. They prevent the banging and stress of pipes.

Here are some of the best ones and easy to install.

Sioux chief

In this Amazon’s choice for arrestors, you’ll find all you need for the perfect fix to pipe problems. It’s so easy to install. It’s rated 4.9 stars for this criteria! Not just this, reviews suggest it’s super value for money. A stainless steel body that won’t be rusting or corroding and is fully reliable.

NameSioux Chief
Item Dimensions LxWxH5 x 3 x 5 inches
Material304 Stainless Steel


  • Sioux Chief is a trusted name.
  • It definitely fixes the problems it’s built for.
  • It saves you a visit from a plumber.
  • It works perfectly being installed straight on the washer.
  • Easy to install


  • We’re bummed it’s not recyclable.
  • In some instances, it only lessens the water hammer.
Sioux Chief 
It has helped thousands of homeowners.

Washing machine special

Your regular arrestor won’t do for your washing machine fitting. Here is the perfect solution to keep your washer and dryer safe from the stress of pipe issues. It’s got a lead-free brass body that is safe and non-toxic. Lead was used in pipelines until it was discovered to be toxic and harmful to humans and animals.

The chamber is stainless steel, so it won’t disappoint you as your pipeline has.

Item Weight‎1.04 pounds
Sizeheight: 2.80 x 1.20 x 3.52 inches


  • Easy to use
  • It works great, vastly reducing the noise.
  • A fair price


  • Won’t solve large noise problems.
  1. Versatile arrestor

It is an arrestor that can easily be installed in any position and any place in your home. It’s compatible with your:

  • toilet
  • shower
  • washing machine
  • and more.

The stainless steel body efficiently absorbs all vibrations, so your system doesn’t have to take the burden.

Item Weight‎3.52 ounces
Package Dimensions‎2.87 x 1.1 x 1.06 inches


  • Great cheap option
  • It made a significant improvement.
  • Easy to install


  • It’s not a complete fix.
It's sold by a reputable manufacturer.

Where to install it

You want to install an arrestor where the pressure is likely to occur. It includes places like near the pump or the check valve. The pipe is changing direction in ideal places, like at the top of the pump riser. As a rule of thumb, you can install it at the end of the branch line next to the last two fixtures it leads to.


You can follow some tips to avoid this problem altogether and save yourself expensive repairs. Here they are:

  • Release air pockets from time to time: Open all faucets of your home at the same time. After some sputtering and spurting, there should be a clear flow. While running, it releases all air pockets present in the system.
  • Install soft-close valves: Use valves that close off slowly and not so tight and fast that they cause too much stress in the system.
  • Close valves half- way: If it is not possible to replace all valves, then close them halfway. It will not abruptly create unwanted tension in the pipes and thus keep the hammering at bay.
  • Install pressure-limiting valve: If you’ve got high-pressure valves, this will lead to problems eventually. It’s better to limit the pressure to an optimum point. Call the nearest plumber and install a regulator to take care of this.
  • Use the right faucets: Modern faucets like hot and cold mixers cause hammers more than standard valves. Check and make sure to buy the right fittings for your home.
  • Install arrestors: This air chamber can cushion the effect of hammers. They come cheap and are super easy to install.
  • Release air chamber: Shut off the main valve and open all faucets. Drain the remaining water until empty. When this happens, the air chamber that might have been waterlogged will be drained. The air chamber will provide cushioning for the prevention of hammers. Now close all the faucets tightly and open the main valve again.
  • Secure the pipe: If you have one particular pipe that is just starting to show problems, prevent them from further damage. Do this by locating the pipe first. See if it has come loose. Tighten and secure it. If not possible on your own, call a professional.

It happens with hot water only.

The rising steam causes more problems with hot water than in regular water. The pressure rises and so does the hammer frequency. But worry not! All you need to do is close the main valve and open up the faucet that’s giving you trouble. Once it is fully drained, all air pockets of steam have been released.

Now open up the main valve and enjoy!

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