Pressure Washer Soap (Full Guide)

Guide To Pressure Washer Soap

Pressure washers are a great cleaning tool for a wide range of different situations and jobs, but they work best when they’re paired with the right chemicals or detergents. Pressure washer soap is specially designed to loosen dirt and get rid of tougher stains, but there are multiple different types that all have different effects on the way your washer deals with certain types of dirt.

Knowing the difference between the different labels and chemical types of pressure washer soaps can make it much easier to choose the right product for the job, especially if you’re under a limited budget or using your gas or electric pressure washer for work purposes. We at Best of Machinery have put together this quick guide that breaks down the differences between them all, along with some of the reasons you might find them useful.

Consumer-Grade Soaps

Soap is a fairly “natural” additive for your washer’s water supply, using a lot of natural fats and oils that are much less likely to damage the surface you’re cleaning. This is especially important for things like untreated wood and bare metal since they can erode or rust easily if they’re not cleaned under the right conditions.

They’re also usually biodegradable, more so that synthetic chemicals, so they won’t cause harm to nearby plants or grass if you’re washing something in the middle of an open garden. Since they’re mostly natural, you can also let soap wash away into drains and sewer pipes without needing to worry about the potential damages, and you can easily get them off your skin if you accidentally spill some onto your hands or arm.

However, they can also cause problems if they’re mixed with hard water (natural water with a high mineral content), creating a layer of scum that’s difficult to remove. They’re great for general use, but if you’re dealing with a lot of a single type of dirt or stain, you might need to use a stronger type.


Detergents are almost always completely synthetic, made out of very specific combinations of chemicals that let them break down certain stains, materials, and other chemical compounds extremely fast while barely affecting others. Since they’re often mixed into the water anyway, they won’t react badly to most water minerals in both soft and hard water, and you might even be able to apply them on their own without mixing them into the electric or gas pressure washer tank itself.

Most industrial-level stains or caked-on types of dirt are best removed with specialized detergents since they can physically break down whatever they’re targeting rather than just pulling it off, and can get rid of greasy or oily layers much faster than soap can. Although they’re usually seen as more toxic and corrosive (which is often true), they generally won’t damage any surfaces they aren’t designed to target, and might even harmlessly drip down rather than sticking to them.

Since most detergents are made of toxic chemicals, they can feel less safe, especially around smaller children and pets, and there’s the added problem of them being in an easy-to-spill liquid form that can take a while to clean up if you drop it. They can be harder to get off your skin in some cases, and might even feel like they’re burning it slightly if you’re using certain chemical compounds.

Commercial-Grade Soaps

Although they’re stronger than consumer soaps, commercial soaps use a very similar mixture of chemicals and often need to be diluted with more water to get the ideal mixture of safety and power. Since they’re more concentrated then regular soap, they work like detergents without most of the downsides, but can still run into problems if they’re mixed with hard water or over-diluted, and they can’t be used on their own as a liquid detergent can.

You can buy commercial-grade soaps in bottles the same size as regular soap types, but they’re more commonly found in bulk, making them more suited to professional cleaners than for use around a single home.

DIY Soaps

It’s possible to make your own soap and detergent mixtures if you have the right chemicals with you, but it’s not something you should attempt without doing basic research first. Some of these DIY creations can be incredibly useful utilities for killing off certain types of damage or dirt – a simple mixture of water and vinegar can kill mildew without harming nearby plants, so you can quickly mix up a bottle on the fly to deal with any mildew or mold you stumble across. To combat mold, use a reliable mold remover.

Pressure Washer Delivery Systems

There are two ways that a pressure washer can use detergents and soaps, downstream (after the pump) and upstream (before the pump). Downstream systems will often let you use more abrasive and corrosive chemicals without damaging the internal parts, but upstream delivery will usually spray the chemicals out with slightly more force. Not all models will let you do both, but it generally comes down to the strength and type of the cleaning liquid you’re using.

Keep in mind that not all pressure washers have an integrated detergent tank – some will only allow you to directly mix chemicals into its main water tank, and others won’t have any way of mixing them together at all, forcing you to use it separately. You also might not be able to use certain types of soap or detergent in certain models depending on the parts they use, so make sure you’ve read the user’s manual or safety guide beforehand.

About the Author

Bob Robinson has been a tool enthusiast and lawn care expert for the past 11 years. First working with John Deere to reduce their impact on the environment, whilst building his love for writing in his spare time. Now, Bob runs the editorial team at BestofMachinery and tends to his garden in his spare time.

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