Pressure washers are powerful tools used for cleaning various surfaces, from cars and driveways to decks and patios. These machines work by using high-pressure water to remove dirt, grime, and other substances. But have you ever wondered what happens to the pressure when you release the trigger and the water stops spraying?

When you are using a pressure washer, the machine builds up pressure by pumping water at a high speed through the nozzle. This creates a strong jet of water that can blast away dirt and stains. However, when you release the trigger, the pressure needs to go somewhere. So where does it go?

When you stop spraying with a pressure washer, the pressure is released back into the machine or into the hose. This is because pressure washers are designed with a safety release valve that allows excess pressure to escape. The valve opens when the trigger is released, redirecting the pressure to the machine or the hose.

It is important to note that releasing the trigger does not mean the pressure washer is completely depressurized. There may still be some pressure left in the machine or the hose. To ensure safety, it is recommended to wait a few seconds after releasing the trigger before disconnecting any hoses or nozzles.

How a Pressure Washer Works

In order to understand where pressure goes when a pressure washer is not spraying, it’s important to first understand how a pressure washer works. A pressure washer is a mechanical device that uses a high-pressure stream of water to remove dirt, grime, and other substances from surfaces.

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Components of a Pressure Washer

A pressure washer consists of several key components:

  • Engine or Motor: This is the power source that drives the pressure washer.
  • Pump: The pump pressurizes the water and directs it through the spray gun.
  • Water Inlet: This is where the water supply hose is connected to the pressure washer.
  • High-Pressure Hose: The high-pressure hose carries pressurized water from the pump to the spray gun.
  • Spray Gun: The spray gun is used to control the flow and direction of the pressurized water.
  • Nozzles: Different nozzles are used to adjust the spray pattern and pressure of the water.

How Pressure is Generated

When the engine or motor is started, it activates the pump, which creates a pressurized stream of water. The water inlet draws water from a water source, such as a garden hose, and the pump pressurizes the water. The pressurized water is then directed through the high-pressure hose and out of the nozzle of the spray gun.

Pressure Relief Valve

When a pressure washer is not spraying, the pressure relief valve comes into play. The pressure relief valve is a safety feature that releases excess pressure from the pump and back into the water inlet. This prevents the pressure from building up and causing damage to the pump or other components of the pressure washer.

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When the trigger on the spray gun is released, the pressure in the high-pressure hose and pump builds up. Once the pressure reaches a certain level, the pressure relief valve opens and allows the excess pressure to escape. This is why you may hear a hissing sound when you release the trigger on a pressure washer.

By releasing the excess pressure, the pressure relief valve ensures that the pressure washer is ready for the next use and prevents any potential damage.


Understanding how a pressure washer works can help explain where the pressure goes when it is not spraying. The pressure relief valve is a crucial component that releases excess pressure back into the water inlet, ensuring the safe and efficient operation of the pressure washer.

Why Pressure Washers Stop Spraying

Pressure washers are powerful tools that use high-pressure water to clean surfaces. However, there are instances when pressure washers stop spraying water, which can be quite frustrating. Here are a few reasons why this might happen:

  • Clogged nozzle: One of the most common reasons why a pressure washer stops spraying is a clogged nozzle. Over time, dirt, debris, and mineral deposits can build up in the nozzle, causing a blockage. Regular maintenance, such as cleaning the nozzle, can help prevent this issue.
  • Low water supply: A pressure washer requires a sufficient water supply to generate high pressure. If the water supply is insufficient, the pressure washer may not be able to spray water properly. Ensure that you have a constant and adequate water supply to the pressure washer.
  • Pump issues: Problems with the pressure washer’s pump can also cause it to stop spraying. A worn-out or damaged pump can lead to a decrease in pressure or complete loss of pressure. Regular maintenance and inspection of the pump can help identify and address any issues early on.
  • Faulty unloader valve: The unloader valve of a pressure washer regulates the pressure and allows water to circulate properly. If the unloader valve is faulty or stuck, it can prevent the pressure washer from spraying water. Checking and fixing any problems with the unloader valve is essential to restore the functionality of the pressure washer.
  • Air in the system: Air trapped in the pressure washer’s system can disrupt the flow of water and cause it to stop spraying. Bleeding the air out of the system can help resolve this issue and restore the proper spraying function.
  • Electrical issues: In some cases, pressure washers may stop spraying due to electrical problems such as a faulty switch or motor. It is important to check the electrical connections and components of the pressure washer to identify and fix any issues.
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Understanding these common reasons can help you troubleshoot and fix the problem when your pressure washer stops spraying water. Regular maintenance, proper cleaning, and timely repairs can ensure that your pressure washer works efficiently and effectively for years to come.

Where Pressure Goes When Not Spraying

When a pressure washer is not spraying, the pressure built up in the system has to go somewhere. The pressure relief valve, also known as the unloader valve, is responsible for releasing this pressure and redirecting it back into the pump. This valve is an essential component of the pressure washer as it helps protect the pump and other parts from damage caused by excessive pressure.

When you release the trigger on a pressure washer, the unloader valve opens, allowing the water to flow back into the pump and preventing the build-up of pressure. It redirects the flow of water so that it doesn’t go out through the nozzle. Instead, it returns to the pump, ready to be pressurized again when you pull the trigger.

Pressure Relief Valve

The pressure relief valve is typically located on the side or the bottom of the pressure washer pump. It is a spring-loaded valve that opens when the pressure inside the pump reaches a certain level. This level is predetermined and set by the manufacturer, ensuring that the pressure doesn’t exceed safe operating limits.

The pressure relief valve is designed to release pressure in a controlled manner. It prevents any sudden surges or bursts of pressure that could damage the pump or the hoses. By redirecting the water back into the pump, it also helps maintain a constant flow of water and maximizes the efficiency of the pressure washer.

Importance of Maintaining the Pressure Relief Valve

The pressure relief valve is a critical component of the pressure washer, and it is important to keep it in good working condition. Regular maintenance and inspection of the valve are necessary to ensure that it is functioning properly. If the valve becomes clogged or damaged, it may not release pressure effectively, leading to potential damage to the pump or other components.

Proper usage of the pressure washer is also crucial in maintaining the integrity of the pressure relief valve. Avoiding prolonged use of the pressure washer without spraying can prevent excessive pressure build-up and reduce the strain on the valve.

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Benefits of the Pressure Relief Valve
Protects the pump from damage
Ensures controlled release of pressure
Maintains a constant flow of water
Maximizes efficiency of the pressure washer

In conclusion, the pressure relief valve plays a vital role in a pressure washer system. It redirects the pressure when not spraying, preventing damage to the pump and maintaining a constant flow of water. Regular maintenance and proper usage of the pressure washer are necessary to ensure the valve’s effectiveness and prolong the lifespan of the equipment.


What happens to the pressure when I’m not using a pressure washer?

When you are not using a pressure washer, the pressure typically stays within the machine. It is important to turn off the pressure washer and release the pressure by squeezing the trigger gun or using the pressure release valve before performing any maintenance or disassembly.

Is it safe to leave the pressure washer with pressure stored inside?

It is generally safe to leave the pressure washer with pressure stored inside, as long as you have properly released the pressure and followed the manufacturer’s instructions for storage. However, it is always recommended to exercise caution and ensure that the pressure washer is securely stored to prevent any accidents.

Can the pressure build up inside the pressure washer over time?

Yes, the pressure can build up inside the pressure washer over time if it is not properly released. This can happen if you forget to release the pressure after using the machine or if there is a malfunction in the pressure release mechanism. It is important to regularly check the pressure release valve and ensure that it is functioning correctly.

What are the risks of not releasing the pressure in a pressure washer?

Not releasing the pressure in a pressure washer can pose several risks. If the pressure builds up inside the machine, it can cause damage to the internal components or even result in an explosion. Additionally, if you attempt to perform any maintenance or disassembly without releasing the pressure, you could be at risk of injury from high-pressure spray or sudden release of pressure.

How do I release the pressure in a pressure washer?

To release the pressure in a pressure washer, you can squeeze the trigger gun or use the pressure release valve. Squeezing the trigger gun will allow the water to flow out, relieving the pressure. The pressure release valve, usually located near the pump, can be opened to release the pressure more directly. It is important to follow the manufacturer’s instructions for proper pressure release.