Using Soap While Pressure Washing (7 Steps for Success)

Published by: | Updated: January 21, 2023
JCS Refresh How To Use Soap With Pressure Washer

Sometimes, you may need more than just water to clean a project.

Grease and oil built up over many months (or years) are particularly difficult to remove, and stains that won’t come out with water alone can be a real pain. 

Even though pressure washers are good at cleaning on their own, adding soap steps things up a bit.

Let’s take a look at how to use soap with a pressure washer, and no, you can’t just use any soap. But, don’t worry, we’ll discuss that too.

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About The Author

Meet the expert behind this article. 



Co-owner & Service Director

Hey there, I’m Cody. 

A decade of residential and commercial pressure washing led me to start JCS Refresh. Now I can share my knowledge with folks like you. 

Do you live in (or near) Seattle, Washington?

Visit our pressure washing pricing page to learn more about our services.

Quick answer

Want to skip the read and jump straight to the steps?

Here’s how to apply soap with your pressure washer:

  1. Prepare all necessary items
  2. Fill your detergent tank with soap
  3. Connect your siphon hose attachment if your pressure washer has no detergent tank
  4. Connect the black low-pressure soap nozzle to the wand’s end
  5. Apply the soap or treatment
  6. Allow your soap to rest on the surface for 10-15 minutes
  7. Attach your preferred high-pressure nozzle and start cleaning

More of a visual learner? Keep reading for the step-by-step guide with illustrations.

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Quick questions before starting

Before you get too excited and start rummaging through your cleaning goods, let’s find out whether this is a simple task and what supplies you’ll need to get started.

How difficult is this to do?

The task has medium difficulty, as it’s essential that you know three things: the type of surface you’re cleaning, the type of soap to use, and how your pressure washer works.

What type of soap is best to use with a pressure washer?

The critical thing to remember is to use soap that’s intended to be used with a pressure washer. Using the wrong product can damage your machine and the surface you’re cleaning. 

  • All-Purpose cleaners: Often on the milder side, they are designed to be safe on most surface types, but that does not mean they are ineffective. It has citric acid, which acts as a stain remover.
  • Vehicle detergents: They are specially formulated without caustic or dangerous ingredients that might damage the paint on your car.
  • House and siding cleaners: Choose one that eliminates mold and mildew, as well as other stubborn stains like rust. Some ingredients are oxalic acid, hydrogen peroxide, and ammonium chloride.
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  • Concrete and driveway cleaners: Best used for concrete floors and pressure washing driveways, these have a higher concentration of citric acid and caustic substances to lift grease, oil, rust stains, and tire marks.
  • Deck and fence cleaners: A cleaner and brightener in one, these products are ideal for removing stains, molds, mildew, and algae from your deck, patio, fences, and other outdoor surfaces.

How much do materials cost?

  • All-Purpose cleaners – $15 to $20 per gallon
  • Vehicle detergents – $70 to $90 per 5 gallons
  • House and siding cleaners – $20 to $25 per gallon
  • Concrete and driveway cleaners – $20 to $22  per gallon
  • Deck and fence cleaners – $20 to $25 per gallon
  • Siphon hose (for pressure washers without a detergent tank) – $10 per 10 feet hose with two filters.

How to use soap with a pressure washer

You know the amount of work needed and the materials to apply soap properly for the first time. 

Now, let’s go through the steps of using soap with your pressure washer.

1. Prepare all necessary items

Get the supplies ready, and be sure to choose the correct type of soap. 

If you need clarification, check the instructions or talk to a professional so you don’t damage the machine or the surface you’re trying to clean.

2. Fill your detergent tank with soap

If your soap is concentrated, dilute it with water within the solution container. Then, pour the soap into the tank.

3. Connect your siphon hose attachment

If your pressure washer doesn’t have a detergent tank, connect one end of the tubing to the pump and the other to the soap solution.

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4. Connect the black low-pressure soap nozzle to the wand’s end

Soap should be used at the lowest pressure possible to ensure it sticks to the cleaned surface.

5. Apply the treatment or soap

To avoid streaks, apply soap to the surface in an upward direction. If necessary, apply another layer to the surface.

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6. Allow your soap to rest on the surface for 10-15 minutes

Let the soap break down dirt and grime so you can quickly rinse. 

When you have multiple surfaces to clean, it’s efficient to have another person apply soap while you rinse other surfaces, so you don’t have to wait 10-15 minutes between surfaces.

7. Attach your preferred high-pressure nozzle and start cleaning

Before getting to the actual cleaning, make sure you know how to use a pressure washer and the safety measures that go with it. 

For example, selecting the wrong nozzle or applying it too closely might harm the surface.

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Safety considerations

Below are several critical considerations to remember next time you use soap with your pressure washer. 

Use soaps explicitly designed for pressure washers

Other chemicals may harm pressure washers. Protect your equipment by using certified soaps and detergents.

Always use the lightest pressure while applying soap

Low-pressure soap application allows the cleaning solution to settle properly. Also, high-pressure application is always risky, and the risk rises with soap.

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Keep the pressure washer wand away from your eyes

Our eyes are delicate and soaps might irritate them, so keep them away from your face.

Don’t point the wand toward yourself or others

Avoid getting soap and dirt on your body, feet, other people, and animals. Also, make sure to wear proper clothing.

Soap vs. Detergent – Which is ideal and why?

Soaps and detergents are often used interchangeably, but there are critical distinctions between the two. 

For example, soap is typically made from natural ingredients such as oils or fats, while detergents are made from synthetic chemicals.

Synthetic chemicals do not necessarily mean that they are harmful to the environment. 

Luckily, as products continue to develop, most are now biodegradable, and harmful chemicals such as phosphates are removed, making them more environmentally friendly. 

For example, phosphate-free detergents prevent the production of large algae blooms, which harm lakes and other local waterways. 

When should you use soaps and detergents when pressure washing? 

We’ve listed the pros and cons so you can decide which to use for your project.




  • Saves time

  • Conserves water

  • Most soaps are eco-friendly and highly concentrated

  • Soap can be purchased for as little as 1 gallon for light cleaning

  • Comes in a variety of types applicable to many surface types


  • Highly concentrated when sold

  • Usually sold in bulk

  • Comes in a variety of types, applicable to many surface types


  • Some products may have a lower concentration

  • Some soaps aren’t available in larger volumes


  • Some detergents aren’t eco-friendly

  • The use of too much concentration may damage the surface

Frequently asked questions

The following are some frequently asked questions that homeowners have about pressure washer soaps.

If you have a question that isn’t answered here, please contact us and someone from our team will get back to you.

How does a pressure washer soap nozzle work?

A pressure washer soap nozzle works by combining soap and water. The mixture is then released through a small hole.

Can you use dish soap in a pressure washer?

We don’t recommend it, mainly because dish soap makes no claims about being compatible with pressure washers and isn’t as effective as other options. Some people prefer to use Dawn and if so, ensure it’s diluted.

Look how clean and refreshed this turned out.

Can you use car wash soap in a pressure washer?

Car wash soaps are foamy and may harm the nozzle. Instead, we recommend using a specialized vehicle detergent.

What detergent is best to use in a pressure washer?

Synthetic detergents work best in pressure washers since they work in both soft and hard water.

Can I use Dawn in my pressure washer?

You may use it after diluting it with hot water, but we don’t recommend it. Dawn is a dish soap; therefore, pressure-washing soap is more effective.

Why is soap not coming out of the pressure washer?

This has many possible causes: clogged nozzles, hoses, and detergent tanks. The wrong nozzle, detergent, or soap was used, or the soap injection mechanism is broken. If this is the case, read our guide about how to fix your soap injector.


Pressure washers are effective, but soaps work as boosters, allowing you to clean even the grimiest surfaces. 

You can clean just about anything with soap and water if you keep these three things in mind: how your machine works, the surface material, and what type of soap to use.

Thanks for reading!