It may occur due to excess water pressure in supply lines, or perhaps plumbing pipes have come loose. Pumps, valves, expansion joints, gasketed joints, and welded joints can be seriously damaged, as can various fittings and connections.
If you hear a vibrating, banging or pounding noise when taps are turned on or off it's usually due to hydraulic shock in your plumbing pipework. Hydraulic shock is more commonly known as “water hammer”. The banging noise you hear is the result of vibrations in pipes.
When the cold or hot water is shut off, the pressure resonates through the pipes, causing them to bang against anything in the vicinity, such as nearby studs, joists or other water pipes. This is the hammer sound that you hear.
Install water hammer arrestors to eliminate the banging.
Water hammer arrestors have air-filled cylinders that absorb the jolt of a sudden water pressure increase when a valve shuts off.
Left untreated, water hammer can lead to actual damage to pipework, appliances and components of any system. Over time this damage can accumulate and result in the premature failure of parts of the plumbing system and all the watery hassle that can cause.
Water hammer can cause serious damage to pipelines, pipe joins gaskets, and all other components of the system like flow meters and pressure gauges. On contact, these pressure spikes can easily exceed five to ten times the working pressure of the system, placing a tremendous amount of stress on the system.
If you are are experiencing noisy pipes, but it only occurs after you use hot water, the culprit is likely expanding copper pipework. This occurs when the pipe rubs against joints, brackets and support structures, or other hidden elements of your home, as it expands with heat.
This sound is called a water hammer and is made when water is forced to stop or change direction suddenly, creating a pressure surge. Simply put, when a water source is turned off abruptly, the flowing water has nowhere to go and instead rushes in reverse back to the water heater, making the banging sound.
The water pressure that passes through the loose pipes causes them to bang against the wall, causing that knocking sound you hear. This problem only occurs while the water is running, so if the banging noise stops the moment you shut off your water, it's a good indication that loose pipes are the culprit.
Enough force from water hammer can even cause pipes to burst. If you hear rattling sounds along with the water hammer, it likely means you have pipes coming loose.
Appliances such as the washing machine, dishwasher or ice maker can be another cause of water hammer around your home. This is because they can cause pressure fluctuations that lead to said water hammers. If the hammer only occurs when one of these appliances is running or is turned off, then you have your culprit.
You can cure water hammer by turning off the water behind the waterlogged chamber, opening the offending faucet and permitting the faucet to drain thoroughly. Once all the water drains from the chamber, air will fill it again and restore the cushion.
To do this, shut off your home's main water valve, then open the highest faucet in your home. Next, turn on the lowest faucet in your home and keep it on until all water has drained. Finally, reopen the main water valve to refill your pipes.
High water pressure is one of most common causes of water pipes knocking. In situations where water pressure is too strong the pipe could shake despite being secured in place on the walls. If it was true then you will be able to tell when the sounds originate only when the water is running.
Let's get straight to it–no, knocking pipes don't automatically spell trouble. But they certainly can lead to problems if you just ignore them. And knocking pipes are easy to ignore at first. Sure, it's a little alarming the first time you hear it, but it's not that loud, and it's easy to get used to.
Water hammer is a key sign that damage may be occurring in your plumbing system. You must fix the cause of water hammer before it results in permanent damage.
Ignoring water hammer can ultimately result in the catastrophic failure of your flow system. The long-term effects of water hammer can include: Pump and Flow System Damage.
Water Hammer
Water hammering is often caused by high water pressure in the pipes, which various factors, such as faulty pressure regulators or a malfunctioning water heater, can cause. It can also be caused by closing a valve too quickly, which can happen when a shower is turned off suddenly.
A faulty toilet fill valve that doesn't close completely or a quick-closing fill valve are both possible causes of water hammer that occurs after you flush a toilet.
Random Hammering Sounds – If your pipes are making a hammering sound, similar to a water hammer but happens at random times, it is usually caused by the water pressure causing loose, rattling pipes. Addressing the loose pipes and installing a pressure reduction valve can help eliminate these hammering sounds.
Water hammer can commonly be caused by trapped air inside the system. Air can find its way into your pipework system if empty pipework is filled too quickly. To minimise the risk of air accumulating with the system, ensure pipework is filled slowly to allow air to escape.
If you're hearing banging noises at random, even while no water is running, it's likely that there's some sediment buildup at the bottom of your water heater. If this is the case, what you're hearing is the resulting reverberations of steam bubbles coming out of that built-up sediment.