Water Tank Size for Pressure Washer

Picture of BISON Santy

Hello, I am Santy, the funder of bisonclean.com. I have been in cleaning machinery field for more than 5 years now, and the purpose of this article is to share with you the knowledge related to pressure washer from a Chinese supplier's perspective.

For those who are in the pressure washing business, you will want to make sure you have a water tank if you are going to pressure wash your clients’ homes. You never know if the water on your working place wether have enough pressure to do the job so that the tank can ensure success.

pressure washer water tank

Can you hook up a tank to a pressure washer?

You can use it as long as your pressure washer has an inlet hose compatible with the tank outlet.

Along with being convenient, the water tank also ensures a constant flow of water through your pressure washer, preventing it from being damaged.

With that in mind, let’s look at everything you need to know to choose the right size tank for your pressure washer.

Tips when purchasing and using a pressure washer tank

  • Before purchasing a tank for your pressure washer, always ensure the tank can deliver the gallons per minute specified for your pressure washer.
  • Before using the tank with a pressure washer, make sure you have a pressure washer filter installed. The water that enters the machine from the tank will be dirty, which can clog or damage the machine.
  • Generally, you will need to install an additional pump between the tank and the pressure washer if the current pressure is insufficient. If you find that the water pressure you are getting is not strong enough, using a normal water pump will help to increase the water pressure.

How many gallons of water does it take to wash a house?

pressure washer water tank 3

The capacity of the tank depends on the tasks you are performing and how long you will be using the pressure washer.

The longer the time, the larger the tank should be so it doesn’t run out during work.

Typically, power washing a home takes about 30 minutes to two hours. Smaller homes around 1,300 square feet can normally be finished in 30 minutes.

A 250-gallon tank is adequate, but not if your cleaning duties are two or more hours long. If your cleaning task takes more than two hours, you should invest in a tank with a capacity of over 250 gallons to ensure you have plenty of room.

It would help if you considered the GPM (gallons per minute) and PSI (pounds per square inch) of your pressure washer, as these are important. A commercial medium-sized pressure washer has a pressure of 2,600 to 3,100 PSI and consumes 2.5 gallons of water per minute.

If you use this machine for 30 minutes, you must ensure you have about 75 gallons of water in the tank. On the other hand, a commercial heavy-duty pressure washer has a pressure of 3,200 to 4,000 PSI and uses 3 to 4 gallons per minute.

If you use 4 gallons per minute and you use it for 30 minutes, you will need 120 gallons of water in the tank.

This example should help you determine how big your tank should be.

How to hook up a tank to a pressure washer

  • First, check the banjo connector when connecting the tank to your pressure washer.


  • Connect the threaded tubing to the fitting, then the inline tubing to the PVC, and use teflon tape to secure it.
  • Attach the ball valve and barb connector, then attach the hose. The barbed connector must be clamped securely so water does not leak from the hose.
  • Connect the hose to the pressure washer water inlet.

Why aren’t you getting enough pressure?

If you’ve connected your tank to your pressure washer and you’re not getting the pressure you want, you should check a few things.

First, check that the hose connections are tight and that the tap to the tank is turned on. 

Then, check to see if the spray wand is set to low or no pressure. If so, adjust it.

Why pressure washer tanks matter

water tank 2

A pressure washer tank is a portable tank designed specifically for power washing. It is made of polyethylene material and comes in many types and sizes, small, medium, and large. While it is very similar to a pressure tank, be aware that they differ in purpose and function.

A pressure washer tank plays an important role in pressure washing. These tanks provide enough force to pull the water out of the pressure washer. In return, it makes the cleaning process easier and enhances water pressure.

But not only that.

Tanks can also help you save water by making the entire process more efficient. Pressure washers are known for their low consumption. Generally speaking, it only consumes a maximum of eight gallons of water per minute. Unlike using a regular garden hose, which can consume 20 gallons of water per minute.

Adding a tank to your pressure washer can significantly reduce the amount of water you consume because dirt, grime, stains, and even mold are instantly removed due to the tank’s added power. Water is being pumped away.

Beyond that, running a pressure washer without water flowing through the system can damage the pump. But connecting the water tank can avoid damage to some parts of the pressure washer, such as seals and gaskets because it can provide a constant supply of running water.

Where does the tank need to be placed?

pressure washer water tank 4

For water to flow easily into the pressure washer, the tank needs to be level with or slightly higher than the pressure washer. This allows water to flow into the pressure washer with the help of gravity. Many people don’t realize they need to do this when using a water tank, and they tend to have problems with a pressure washer. The water tank can provide you with a constant flow of water through the pressure washer. You don’t necessarily need to do this if you use a garden hose to fill the pressure washer with water, although it’s probably a good idea to keep the hose level with the pressure washer.

Pressure washers can be supplied with water directly from a tank, eliminating the need for a pump to push water from a container to the machine. It is best to place the pressure washer as close to the water source as possible and extend the high-pressure hose to reach the cleaning location. If you place your pressure washer too far from a water source, it may take you longer to clean the item you are cleaning because it takes longer for the pressure washer to pump the water into the system.

If you start your pressure washer engine without first running water through the pressure washer system, you can damage the pump gaskets, seals, and other parts. If you damage or destroy the pump and cause it to fail or cause damage to any other component, it can be costly to repair your pressure washer, and you may need to purchase another one.

Standard size

In pressure washing, the tank size affects the amount of water released. Based on standard rules, these are typical dimensions:

0-10 GPM: Reduce flow by one gallon for every 1 GPM of flow

10-20 GPM: Reduce flow by one and a half gallons for every 1 GPM of flow

20+ GPM: 2 gallons drawdown for every 1 GPM of flow

For further understanding, a drawdown is a term used to refer to a tank pumping and releasing water through pent-up pressure.

So the answer to how big a tank you need depends on the area you are cleaning. For example, if you plan to clean large areas with a lot of dirt and stains, purchasing a tank with a flow setting of 10-20 GPM is best. Otherwise, a tank setting of 0-10 GPM is sufficient.

What are the dimensions of a 500-gallon tank?

The size of the 500-gallon tank varies depending on the shape and orientation of the tank. For a standard 500-gallon tank with a basic rectangular or cylindrical shape, the dimensions are usually about 48 inches high and 72 inches wide.

Height and width also depend on the orientation of the tank. If the tank were placed vertically, the diameter would be 48 inches high and 36 inches wide. Depending on the chosen direction, horizontal tanks may have a greater width.

A 500-gallon tank may also vary in thickness depending on the material from which it is constructed. Typically, tanks are made of steel (4 to 7 mm thick) or molded plastic, ranging in thickness from 1/4 inch to 5/8 inch.

Pressure Washer Water Tank Size FAQs

While this might seem like a good idea, it often doesn’t work. If you want to try it, you will need a pressure washer compatible with the suction hose. However, the water contains impurities, so a filter is required.

If your rain barrel has an outlet at the bottom, you can attach a hose or suction hose to connect it to a small pressure washer. However, the pressure needs to be high enough for a pressure washer.

As mentioned above, the tank size affects the drawdown or operating pressure accordingly. Therefore, the higher the working pressure, the larger the tank.


Remember that the two are related, the pressure washer and the tank, and when one of them changes, it must be adjusted accordingly. Therefore, if one increases or decreases, the other must also increase or decrease.


If the pressure is high, then the drawdown is low. In this case, you will need a tank with ample space.

You can use the tank with both gas and electric pressure washers. Fortunately, it doesn’t matter whether a gas engine or an electric motor powers your pressure washer. You can run a pressure washer from the tank in the same way. Every pressure washer has a pump that puts pressure on the water and squeezes it out of the spray wand, no matter the water source. However, the type of nozzle you use matters when it comes to cleaning. The nozzle type depends on how clean you want the surface to be.

Some pressure washers will work when they have a gravity-fed water source, but most will not. Low-quality pressure washers won’t work when the water supply isn’t pressurized. Many low-quality pressure washers require a water source of at least 20 psi.


A high-quality pressure washer can be used with a gravity-fed water source, but it depends on how high-quality the pressure washer is. A high-pressure washer will work well if the water source also has a pump because they don’t have to work as hard to pressurize the water.

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