Pipe knocking when the shower is on can be a nuisance and may indicate an underlying issue with the plumbing system. So it is important to address this issue as soon as possible to prevent further damage to the pipes and ensure that the plumbing system is functioning properly.
Several factors can cause pipe knocking when the shower is on. We discuss them in detail below.
Water Hammer
Water hammer is a common plumbing problem when water flowing through pipes is suddenly stopped or slowed down, causing a shock wave or “hammer” effect. This can cause pipes to vibrate and make knocking or banging noises, particularly when a shower is turned on or off.
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.
To fix a water hammer, you can install a water hammer arrestor, which absorbs the shock wave caused by the sudden change in water flow. Adjust the water pressure in your pipes by installing a pressure regulator or repairing any leaks or faulty valves.
It’s also worth noting that a water hammer can be a sign of other plumbing issues, such as faulty pipes or a failing water heater.
High Water Pressure
High water pressure can cause pipe knocking when the shower is turned on because it puts extra stress on the pipes. When the water pressure is too high, it can cause the pipes to vibrate and make a knocking sound. This can happen when the water is flowing through the pipes at a high velocity, which can be caused by several factors, which include the below.
A faulty pressure-reducing valve is installed on the main water line to regulate the water pressure coming into the house. If it is not functioning properly, it can cause the water pressure to become too high, leading to pipe knocking.
A water main that is too high: If the water main is located above the house, the water will naturally have a higher pressure when it enters the pipes. This can be especially problematic if the pipes are not designed to handle high pressure.
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Loose Supply Pipes
When pipes are not securely fastened, they can vibrate and make knocking or banging noises when water flows through them. This can be particularly noticeable when the shower is turned on or off, as the sudden change in water flow can cause the pipes to vibrate more.
To fix loose supply pipes and the associated pipe knocking, you will need to secure the pipes in place. This can typically be done by tightening the mounting brackets or clamps that hold the pipes in place or adding additional brackets or clamps if necessary. You may also need to repair or replace any damaged or corroded pipes.
Bottom Line
Pipe knocking when the shower is turned on can be caused by several factors, including high water pressure, water hammer, and corrosion or damage to the pipes. It is important to address this issue as soon as possible to prevent further damage to the pipes and to ensure that the plumbing system is functioning properly.
If you are experiencing pipe knocking when the shower is turned on, it is a good idea to have a plumber assess the situation and determine the cause of action.
Related Plumbing & Sewer Resources
Knocking pipes may indicate plumbing or hidden sewer issues.