Can You Gravity Feed a Pressure Washer?

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No matter the task, a pressure washer will always need a steady supply of water. One topic that usually comes up is if you can gravity feed a pressure washer using different means. That is what this post is going to answer and also explain related concepts to this topic.

You can gravity feed a pressure washer if there is sufficient pressure and water. At the bare minimum there should be 20 psi and 1 gallon per minute (GPM). Keep in mind that some pressure washers are not designed to work with gravity feeding systems, so check your owner’s manual first.

Can You Gravity Feed Pressure Washers from a Tank?

Most pressure washers can be gravity fed from a tank. For this to work, the tank must be in an elevated position. The GPM and psi must also meet the minimum requirements needed by your pressure washer.

Not all gas and electric pressure washers accept gravity feeding from tanks. Check your owner’s manual before proceeding just to be safe. Most of the time your washer should have no issues with this, but there are always exceptions.

If your pressure washer comes with an inlet hose, check if it fits with your water tank outlet. If yes, you can gravity feed the washer. How much water you can draw depends on the pressure washer and its GPM capacity.

One reason why some manufacturers discourage gravity feeding is it makes self-priming hard. Ideally the pump should be lubricated by water before you turn it on.

This is why you have to make sure the gravity feed has delivered water to the pump before proceeding. Starting a pressure washer without water is a bad idea.

Some pressure washers do not disallow gravity feeds, but suggest to make sure the flow is enough. If the pressure washer is lower than the tank, there should be no issues.

How to Gravity Feed a Pressure Washer from a Tank

If your pressure washer accepts gravity feeding, yes it is possible. Follow these steps.

  1. Note the GPM and psi requirements of your pressure washer. The Rock&Rocker pressure washer has a limit of 2150 PSI and 2.6 GPM. This has to be met by the gravity feeding system, in this case a water tank. The minimum is usually 20 psi and 1 GPM.
  2. Position the water tank higher than the pressure washer. The higher you can place the tank, the better.
  3. Plug one end of a suction hose to the pressure washer and the other end to the tank. Usually this means the 3/4 end to the washer and 1 inch to the tank. Yours might be different.
  4. Turn on the washer. Use a gauge to check the GPM and psi. If they at least meet the minimum requirements, you should be fine.

The important thing is to use a rigid hose so it remains steady. An ordinary garden hose will not suffice so get a suction hose for this.

How to Boost Water Pressure on Gravity Feeding Systems

Gravity fed systems are classified as low pressure because it relies solely on gravity. The best way to increase pressure is to move the water source onto a higher location.

If the GPM and psi are too low, you have to make adjustments. One solution is to get a washer that runs with little pressure. Many electric pressure washers need as little as 20 psi, so that is a good option.

But if you need more psi and GPM, increase the pressure from the tank. You can do this by moving the tank to a higher spot. This can work with a light tank, but if it is heavy, can be difficult.

The higher and further the water falls, the greater the impact and pressure. This is how it works with shower systems and the same principle applies to pressure washers.

Use a Suction Hose

Another thing you should do is use a stiff suction hose, without any pinch or bend. The Kärcher 26431000 5 is a nice example of this hose. What you want to do is replicate a gravity fed shower which uses a long pipe.

In this case the hose has to function like a pipe. The stiffer the hose and the higher the water source the better. You might even want to use two stiff hoses with your washer.

It is better to use a short, large hose to keep the pressure up. Of course you also have to keep the water source as high as possible.

Inlet Filter and More Pumps

Proper maintenance improves pressure washer performance, particularly the inlet filter. Place the inlet filter between the pressure washer and hose so it can do its work.

Most pressure washers have an inlet filter, and if yours does not, get one. The filter will keep dirt away from the water and make it easier for water to flow.

Another way to boost the pressure is to install another pump. It can be any type of water pump as long as it supplies the minimum GPM and psi needed by your pressure washer.

Two things to keep in mind: make sure there is water in the pump before you turn on the washer. Second, do not let the hose collapse. If it does this could damage the pump and cause major problems. If you have problems with the pressure washer pump, you have to fix it first.

Can You Gravity Feed Pressure Washers from a Rain Barrel?

Yes, you should be able to use a pressure washer with a rain barrel. Use a suction hose if possible, or plug a hose onto the barrel outlet, usually around the bottom.

Once plugged in the pressure washer should work. How successful it is depends on the same factors as on a water tank. So if you want to use a rain barrel, place it on an elevated spot. The higher the location the more pressure when it drops.

You should use a hard hose with the rain barrel. Avoid hoses that easily bend and opt for a short, large hose. If the pressure is not enough, add another pump.

Image: Alex Cua

Can You Draw Water from a Lake with a Pressure Washer? Theoretically it is possible but it is difficult. You must have a suction hose and keep the distance between the pressure washer and hose as small as possible.

Even then the pressure might not be sufficient. You may want to try electric pressure washers or even a submersible pump instead. If you do opt to draw from a lake, have those filters ready to remove the dirt.

Frequently Asked Questions

Why is my pressure washer not drawing water?

If your pressure washer is being gravity fed from a tank and is not working, check the GPM and psi. If the numbers are lower than the washer requirements, you need to boost the water pressure. Either move the tank higher or use another washer that runs on lower GPM or psi.

How large should the water tank be?

It has to be large enough to meet the GPM and psi you need. This is not so much about the physical size of the tank as the volume of water and how much pressure they produce.

Can you use a pressure washer with a static tank?

If the pressure washer comes with an inlet hose, yes it will work.

Do pressure washers need pressurized water?

Yes, pressure is required for water to flow out of the nozzle. The amount of pressure varies, but some of it is needed for any type of washer to work.

Can you feed a pressure washer from a bucket of water?

This will work if you have a suction hose. Whether you have a tank, barrel or bucket, it is best to use a suction hose and position the water container as high as possible.

Is it possible to run a pressure washer with low pressure?

Some pressure washers will work with 1 to 2.5 GPM, so the answer is yes. The key is to make sure the water supply source provides the volume and pressure needed to get the washer running.