A machine gun sound coming from the shower pipes when you turn on the water is a cause for concern.
If ignored, the noise will worsen and could result in damage to the pipes and parts of the bathroom.
Machine gun sounds from the shower are most commonly caused by water pressure issues. The cause can also be loose pipes, water inside the air chamber, an issue with the cartridges or a clogged showerhead. Most of these can be fixed quickly and easily without a plumber.
5 Causes Of Rattling Shower Pipes
Below are the 5 most common causes of machine gun sounds when you turn on the water for the shower:
1. Water Pressure
One of the most frequent causes of machine gun noise from the shower is an imbalance of water pressure.
An imbalance can “water hammer” which is a hydraulic shock when the valve of a high-pressure water line closes. The water hits against the pipes or the closed valve and this causes the pipe to jerk and hit against other nearby pipes.
2. Issues With The Pipes
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The sound could be the result of the pipes that are carrying the water to the shower being loose.
Loose pipes move around and rattle when the shower is turned on. The sound of the pipes moving around and hitting into each other or the surrounding wall can be similar to a machine gun.
3. Water Inside The Air Chamber
The plumbing line has an air chamber which helps to cushion the shock caused by water reaching shut-off valves. This air chamber prevents the pipes from moving and hitting into each other.
However, the air chamber can get water inside when there is a leak or a worn valve.
When the air chamber is waterlogged, there is nothing to cushion the shockwaves. This causes the machine gun noise.
The water inside the air chamber damages the plumbing lines so need to be fixed quickly.
4. Clogged or Damaged Faucet Cartridges
The cause could be the result of faulty, damaged, or loosened faucet cartridges.
The problem can be solved by replacing the cartridge. The cartridges are simple to fix and replace yourself.
The process can depend on the type of shower faucet you have.
5. Clogged Showerhead
Finally, if the sound is coming from the shower itself then the issue might be the showerhead.
Limescale can clog the showerhead which can reduce the space and cause the water to have a narrow route. This increases the water pressure and can cause noise.
Clean the showerhead and unclog it to help the water flow without issues.
5 Ways To Fix A Shower That Sounds Like A Machine Gun
Below are 5 simple fixes that can help you solve the problem without needing a plumber:
1. Stabilize The Pipes
Over time the straps that are holding the pipes in place can loosen. This allows the pipes to move around and make noise.
Tighten the straps to stabilize the pipes and stop them from rattling. It can be difficult to locate and access the loose straps but once located, it’s a quick fix.
2. Fix Waterlogged Air Chambers
If waterlogged air chambers are the issue, follow these steps to create new air chambers within the system:
- Turn off the water supply to the house.
- Open the highest faucet in the house and then open the lowest faucet in the house.
- Wait until the water has completely drained from the faucets and then turn the water supply back on (while the faucets are still on). The pipes will refill and there should now be new air chambers.
- Turn the faucets off then turn on the shower and listen for machine gun sounds. If the shower is now quiet, waterlogged air chambers were the issue.
3. Replace The Faucet Cartridge
One of the easiest fixes to this issue is replacing the cartridges of the shower faucet:
- Turn the water supply to the shower off.
- Locate the mounting screw on the faucet handle and use a screwdriver to remove it. Put the mounting screw to one side.
- Lift the faucet handle and remove the screw holding the escutcheon plate in place. Remove the protective plate and put it on one side.
- The cartridge should now be visible. Use pliers to take hold of the cartridge and turn it counterclockwise to loosen it. Once loose, remove the rubber washer (it should just slip off) and put a new washer in its place. If needed, replace the whole cartridge.
- Once the cartridge is in position, use the pliers to tighten it and screw the escutcheon plate and the faucet handle back into place.
- Once all parts are back in position, turn the water on and test the shower. If the machine gun sound has gone the cause was a worn or damaged cartridge.
4. Reduce The Water Pressure
High water pressure can cause the machine gun sound. Over time, this can cause further damage including leaks.
Some homes have a constant pressure well pump or a pressure reduction valve which allows you to set the pressure easily. In this case, set the pressure to 50 PSI.
According to Water Defense, pressure higher than 70 PSI is too high and will put pressure on the plumbing system. Water pressure higher than 100 PSI can damage the plumbing and cause leaks.
If there is not a water pressure reduction valve in your home then it is best to call a plumber to make the required adjustments.
- Look for the water regulator and turn off the water valve.
- Loosen the adjustment bolt nut until it rotates.
- Turn the bolt to reduce the water pressure then test the tap. Turn the pressure down more if needed.
- Tighten the adjustment bolt nut to lock it in place.
5. Install Hammer Arrestors
Water hammer arrestors absorb shock and work in the same way as air chambers. Installing these devices between the shut off valve and the water supply line can solve the problem.
Install an arrestor in the cold water valve and in the hot water valve of the shower.
If you are noticing a machine gun sound when you turn on other faucets, install hammer arrestors at those valves too.
Water hammer arrestors can be installed yourself or by a plumber. It is best to call a plumber as the process can be challenging, particularly if you are not experienced.
In Summary
Although a machine gun sound coming from the shower sounds intimidating, it is actually a relatively quick and inexpensive fix.
In most cases, you should be able to fix the problem yourself. Although a plumber can help if you are struggling to find the cause or are unsure about what to do.