How to: Fix a pressure washer with low or no pressure

Pressure washers are of best use when there is an adequate amount of pressure! It is through the force of the water that surfaces become clean and sterilized. Without pressure, can they adequately be called pressure washers?

Little or no pressure when using a pressure washer is normally caused by worn out equipment, debris build-up, or wrongly sized equipment. It can also be caused by kinks in the hose, or air in the system. Most of these can be fixed through re-adjustment, cleaning, or replacement.

As you can see, there are a variety of reasons that can be the cause of a low pressure situation. Each of these problems come with different situations, but it is important to know which is the stem of your pressure problem so that you can find the quickest solutions.

Before you begin looking into why your pressure washer is not holding pressure, it may be important to find out if the problem is coming from the hose or from the pump itself. In order to find out the answer to this, detach the hose from the pump and run the water though, does it have good pressure or not?

If not, then there is probably a kink in your hose or something else happening up the line, but if the water comes out of the hose fine, you know that something within the pump is causing the problem. This gives you a better place to start.

Dirt & Debris

The buildup of dirt or rocks will likely cause you to lose a significant amount of pressure. At any point in time, something can come through the system that is likely to get stuck. If this happens, the pressure of the water will drop and the cleaning you had planned won’t be effective. In order to combat this, it is important to clean the pump and the hose regularly.

Check the filter, the screen, the nozzle, and the hose all for possible areas where dirt could build up and reduce the water flow. This is possible as you take apart the pressure washer and run water throughout the system to remove the build-up.

Another great way to prevent this is to check your water source occasionally. If you have a slimy, unclean water source there is a higher chance of getting more build up in your system. If your water source is clean, pure water, then you are less likely to have problems with build-up. If the water is unclean, it may be smart to first run the water through a water filter before it goes to your pump. Though, the water source should be checked every couple of months to ensure it is clean, and the machine should be routinely cleaned.

Plus, who wants to supply a pressure washer that is meant to clean with water that will ultimately get everything you spray dirty. Keep the water source clean, as well as all the equipment. Water temperature can also affect the pressure. If your pressure washer is meant to use cold water, use cold, if its a power washer and uses hot water, then use hot water. Switching them can cause a slight decrease in pressure.


When using a pressure washer, the most important factor is the water. You not only need it to actually do the cleaning job, but the machine also needs the water in order to function properly. If your pressure begins to fail, check to make sure that the machine is getting the adequate amount of water it needs. “Most washers require a continuous water supply of about 4L per minute to operate normally” source. If you are using a well or something similar as a water source, you may find that the pressure will vary overtime. It may be more helpful to use a steady supply of water.

The hose can also be a major pressure culprit. The slightest kink can ruin the whole operation. If you unscrew the hose and find that not even it has good pressure, check the entire hose for kinks or holes and un-kink them, as well as patching up holes. It is also important to make sure that the hose you are using is the correct size. Most pressure washer manuals state that the connected hose should be 3/4″ diameter hose in order to channel the correct amount of water.

On each machine it also will give specifications on how the long hose should be. If the hose is longer than needed it will reduce pressure throughout the whole system. Check the specifications and ensure your hose is the right length.

Unloader Valve

“Pressure washers are equipped with an unloader valve which bypasses the flow of water back to the pump when the spray gun is not being used. Unloader valves also regulate the output pressure of the pump” source. This valve could also be a culprit of your low pressure. You should first make small adjustments to it and see if it has somehow turned down the pressure. When doing this, be sure to only make minor adjustments at a time so that the pressure stays within the appropriate range.

If this valve is worn out, and it is not regulating pressure adequately, then it will need to be replaced. It could also be housing build-up and debris that should be removed. If you begin making adjustments to the pressure, be sure that the machine is on and the trigger to release water is pulled so you can see the increase and decrease of pressure. If when you adjust the pressure it does nothing, you will probably need to replace that valve.


Nozzles work by “restricting the water flow from a continuous pressure source [which in turn] creates more velocity (speed), which creates more force (pressure) in the spray.” Nozzles have little holes in them which pressurizes the water as it is released. Nozzles can become worn out, or they can become clogged, and both of these may cause a loss of pressure within your system.

In order to tell which may be the problem, pay close attention to the water. Is it coming out of the hose sporadically? Or it the hose just gradually losing pressure over time? If the water is coming out sporadically, it is likely that the nozzle is clogged. To fix this you can unscrew the nozzle and ensure that the line and nozzle no longer have dirt or small rocks in them. If you water is just gradually losing pressure the more you use it, your nozzle is probably worn out and the small hole which pressurized the water is getting larger and leading to less and less pressure. Replace your nozzle if this is the case.

Worn Out Pump

Lastly, if your have a worn out pump, then it wont be pumping the water throughout the system and creating that desired pressure. There are a variety of reasons that you would have a worn out pump, even though pressure washers normally do not get enough use to get worn out to quickly. “Premature wear can be caused by not changing the oil, using the wrong oil or lubricant, water getting into the pump housing or running the power washer with no water running through it” source. Once you have worn out a pump, about all you can do is replace it, and hopefully then the low pressure will return to adequate pressure.


In the end, there are all sorts of small factors that can contribute to low pressure, it is just about trial and error. Always be observant and hopefully you will be able to find the problem quickly and effectively. Really, you just need to ensure that you are keeping your equipment clean and changing needed supplies like the filter and the oil. Also be sure to check the wear and tear of various parts throughout the machine. This will not only keep the pressure from dropping, but it will keep you much safer while using it. Here is a short list of other possible causes that may be worth looking into if nothing has worked from the list above so far:

  • Shattered or Broken Water Pump – this will happen if there is not enough oil or the oil has not been changed.
  • Pressure Regulator – this is on some pressure washers in place of a unloader valve.
  • Engine Malfunctions – if the engine is not working properly, it is likely that water will not be pressuring up.
  • Bad Quality Equipment – if you bought the cheapest of all pressure washers, it could be possible that it just wont work because of that.
  • Air in the System – pressure washers are not huge fans of air, and if air is caught in the system it will cause the water to come out sporadically.
  • No Nozzle or Incorrect Nozzle – always check to ensure that you have a nozzle, and that the nozzle is sized correctly. Also ensure that the nozzle is the right size for the pressure you desire.

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