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Sure, you can clean driveways, siding, decks, and automobiles by hand, but a pressure washer loaded with pressure washer soap will save a lot of time and elbow grease. When paired with the best power washer detergent, a pressure washer can make a stained driveway or dirty home exterior look almost new again. The best soaps for pressure washers are designed to remove dirt, mildew, grease, and grime, and they typically do so by utilizing safe, eco-friendly ingredients.
We use pressure washers for many outdoor cleaning chores, so we were excited to see whether they would clean better if we used them with specifically designed soaps. To do so, we tested eight of the top pressure washer formulations on the market. We cleaned cars, driveways, siding, fences, motorcycles, and more, noting which cleaners performed the best in the process.
Ahead, learn more about the qualities to look for in this type of cleaning product and find out how the following products earned a spot on this lineup of the best pressure washer soaps.
- BEST OVERALL: Sun Joe Heavy-Duty Pressure-Washer-Rated Cleaner
- BEST BANG FOR THE BUCK: Karcher All-Purpose Detergent for Pressure Washers
- BEST ENVIRONMENTALLY SAFE: Simple Green Oxy Solve Total Outdoor Cleaner
- BEST FOR CARS: Karcher Vehicle Wash and Wax Detergent
- BEST FOR DECKS: Zep Wood Deck and Fence Pressure Wash Cleaner
- BEST FOR SIDING: Krud Kutter House and Siding Pressure Washer Soap
- BEST FOR DRIVEWAYS: Simple Green Oxy Solve Concrete and Driveway Cleaner
- ALSO CONSIDER: Zep All-In-1 Premium Pressure Wash Cleaner
How We Tested the Best Pressure Washer Soaps
Before selecting pressure-washing soaps for hands-on testing, we carefully researched more than 35 different types. We considered the brand name to an extent—after all, names like Karcher and Sun Joe are well respected in the detergent industry for good reason. Still, we didn’t automatically eliminate smaller or up-and-coming brands if consumers ranked their products highly.
We selected soaps in various categories, looking for the best performers while keeping an eye out for eco-friendly products.
In testing, we filled the soap dispensers of our pressure washers (or we diluted the detergent in a 5-gallon bucket, if applicable) and started washing. We tested each pressure washer soap on the appropriate surfaces. If it was meant for cars, we washed cars or motorcycles. If it was made to clean exterior wood, we used it on decks or fences.
As we conducted our tests, we awarded points via a rubric—the better a soap was at cleaning a listed surface, the higher the points it received. We also awarded points for good-smelling (or non-scented) soaps and noted whether they left any residue. After testing, we averaged the points and used them to determine our top performers and categorize each by its best use.
Testing Stats
- Products tested: 8
- Hours spent testing: 10+
- Tests performed: Cleaning stains, cleaning grease, odor detection, surface inspection
- Average price: $25.50 per gallon
Our Top Picks
The following picks include all-purpose pressure washer cleaners and some formulated to suit specific jobs. Each one was extensively tested to see if it stood up to the manufacturer’s claims. One is sure to be a good pick for your outdoor pressure-washing projects.
Best Overall
Sun Joe Heavy-Duty Pressure-Washer-Rated Cleaner
Our Ratings: Ease of Use 5/5; Effectiveness 4.5/5; Scent 5/5; Value 5/5
Product Specs
- Type: Concentrated
- Surfaces: All-purpose (wood, metal, vinyl, masonry, etc.)
- Biodegradable: Yes
Pros
- The all-purpose formula is suitable for cleaning multiple surfaces, making it a versatile choice
- Biodegradable and safe for use around grass, wildlife, plants, and pets
- Can be poured into the soap reservoir of a pressure washer or diluted for spot-cleaning
Cons
- May not be as strong as some specialized cleaners; grease may require additional cleaning
With its all-purpose formula, Sun Joe’s pressure washer cleaner is a great option for cleaning various surfaces around the house and yard. It effectively removes dirt and grime from multiple surfaces.
We filled up the soap reservoir of our power washer with the Sun Joe cleaner and tested its cleaning performance on a concrete driveway, truck tires with a thick layer of dried-on mud, and cement-fiber siding. The cleaner did a great job powering away dirt and mud, and it didn’t seem to leave any residue behind. It also cleaned away the majority of some old grease spots on the driveway, but not completely; a shadow of the stained area was still visible after a thorough power-cleaning. Still, it was much better than before.
The cleaner is concentrated, so the 1-gallon bottle goes a long way. Sun Joe’s formula is biodegradable and safe for use around landscaping, wildlife, and family pets, and we didn’t notice any lingering odor or scent. In addition to being poured directly into the soap reservoir of a power washer, it can be diluted in a bucket of water and applied using a mop or brush for spot-cleaning areas unsuitable for pressure washing.
Get the Sun Joe pressure washer soap at Amazon, Lowe’s, Walmart, or The Home Depot.
Best Bang for the Buck
Karcher All-Purpose Detergent for Pressure Washers
Our Ratings: Ease of Use 4.5/5; Effectiveness 4.5/5; Scent 4/5; Value 5/5
Product Specs
- Type: Concentrated
- Surfaces: All-purpose (wood, metal, vinyl, masonry, etc.)
- Biodegradable: Yes
Pros
- Cost-effective concentrated solution, with 1 gallon producing up to 20 gallons of cleaner
- Solution is biodegradable and suitable for use around landscaping and pets
- Versatile and suitable for use on several types of surfaces, including wood, brick, and metal
Cons
- May leave a slight residue on some surfaces and require rinsing
Budget-minded consumers would be hard-pressed to find a more affordable cleaner than this pressure washer soap from Karcher. It costs less than many pressure washer cleaners, and 1 gallon can produce up to 20 gallons of cleaner.
We tested the Karcher solution by pressure-cleaning a concrete sidewalk, a brick landscape border, and some muddy truck tires. The solution easily cleaned away dirt and mud but left a faint hint of oil stains behind. We also noticed a slight residue after we’d cleaned the bricks, but it rinsed away quickly when we switched to plain water.
In addition to being versatile, this pressure washer detergent is biodegradable, so it’s safe to use around landscaping and pets. It comes in 1-gallon and 1-quart bottles, though for maximum savings, it makes the best sense to go with the larger container.
The solution has a slight scent we detected during washing, but it wasn’t overwhelming or off-putting, nor did it linger. In short, this is the best power washer soap for general cleaning purposes at an attractive price point.
Get the Karcher all-purpose pressure washer soap at Amazon or The Home Depot.
Best Environmentally Safe
Simple Green Oxy Solve Total Outdoor Cleaner
Our Ratings: Ease of Use 5/5; Effectiveness 4/5; Scent 4.5/5; Value 5/5
Product Specs
- Type: Concentrated
- Surfaces: All-purpose (wood, metal, vinyl, masonry, etc.)
- Biodegradable: Yes
Pros
- Eco-friendly; meets high sustainability standards of the Amazon Climate Pledge Friendly and EPA Safer Choice Program
- Effective at removing embedded dirt and mud from porous concrete and stucco surfaces
- Compatible with multiple surface materials, including concrete, brick, plastic, and more
Cons
- Didn’t remove rust stains around screws in a wood fence, though it did deep-clean the wood
Many pressure washer soaps are biodegradable and safe for the environment. However, the Simple Green Oxy Solve cleaner is one of a handful that makes Amazon’s Climate Pledge Friendly list. It also meets the high sustainability standards of the EPA’s Safer Choice Program. The cleaner uses the eco-friendly power of hydrogen peroxide to clean.
We tested Oxy Solve for pressure-washing a concrete sidewalk, stucco siding, and a wood fence. It performed very well on the concrete and stucco, removing even embedded dirt and mud. It also did well on the wood fence, removing dirt and dinge and making it look newer. However, it wasn’t able to remove rust stains around the screws in the fence rail.
We thought we detected a light, fresh scent as we power-washed with Oxy Solve, but it was so faint that we might have just imagined it. A big perk with this cleaner is that it left no residue behind, so we didn’t have to spend time rinsing.
In addition to contributing to this cleaner’s environmentally safe designation, hydrogen peroxide is compatible with many surfaces. This includes masonry, plastic, metal, vinyl, wood, and even fabric. It can be used in a pressure washer, as we used it, or it can be diluted and brushed or sponged on. A single gallon of Simple Green Oxy Solve makes up to 21 gallons of cleaner.
Get the Simple Green Total Outdoor Cleaner pressure washer soap at Amazon or Walmart.
Best for Cars
Karcher Vehicle Wash and Wax Detergent
Our Ratings: Ease of Use 4.4/5; Effectiveness 4.5/5; Scent 4.5/5; Value 5/5
Product Specs
- Type: Concentrated
- Surfaces: Vehicles
- Biodegradable: Yes
Pros
- Powers away dirt and road grime and leaves a shiny luster on cars
- Can be applied with a foaming attachment on the power washer
- Specifically designed for use on automobiles, motorcycles, and similar vehicles
Cons
- May leave a slightly dull finish unless hand-dried with a chamois
When you’re selecting the best soap for power washing a car, cleaners that leave streaks simply won’t cut it. Karcher’s formula is designed to leave a clean finish thanks to a soap mix that rinses away grime and leaves a shiny luster on the car after rinsing.
We tested this cleaner on a car and a motorcycle, using a foaming attachment on our power washer to apply it evenly. We sprayed the Karcher solution on one side of the car, let it sit for about 5 minutes, and then rinsed it off. On the other side, we applied the solution, used a soft car-cleaning brush to scrub away stuck-on highway grime, and then rinsed it off. Both sides were much cleaner, but the side we scrubbed was the cleanest.
This solution leaves a film—the wax. We found that we got the best shine when we rinsed away all the soap with clear water and then dried the car with a chamois. When we let the car air-dry, it looked a little dull.
The formulation is biodegradable, so it won’t harm grass or landscaping when it runs off the driveway. We really liked this power washer soap, but it’s only for automobiles, motorcycles, boats, and similar items. For the best-finished shine, be sure to dry with a chamois.
Get the Karcher Vehicle Wash pressure wash soap at Amazon, The Home Depot (32 ounces), or Walmart.
Best for Decks
Zep Wood Deck and Fence Pressure Wash Cleaner
Our Ratings: Ease of Use 4.5/5; Effectiveness 4.5/5; Scent 4/5; Value 4.5/5
Product Specs
- Type: Concentrated
- Surfaces: Decks and fences
- Biodegradable: Not specified
Pros
- Effective for removing mold, mildew, and algae stains from exterior wood surfaces
- Restores the appearance of aged wood for a brighter, cleaner look
- Suitable for use on composite decking and PVC surfaces as well
Cons
- Not recommended for use on painted or stained wood surfaces
Over time, exterior wood can develop mold and mildew, leaving it looking drab and nothing like it did when it was new. Whether you just want a cleaner look or you’re prepping the wood for a new finish, Zep pressure washer soap can help.
We tested the cleaning solution on a small treated-wood deck and on a cedar gate. The first thing we noticed was how the wood looked much cleaner as we were going, even though it was wet. When the wood dried, both the deck and the gate looked brighter, and the natural wood tones stood out more. The difference was especially noticeable on a section of deck railing that had darkened with mold. Zep stripped away the mold stain and left that area looking new.
Zep is specially formulated for the job with its ability to kill and remove mold and mildew. It also brightens wood as it cleans, ensuring good results when the deck is refinished. The product also works on composite and PVC decking.
The formula is diluted, so 1 gallon produces more than enough cleaner to wash up to 5,000 square feet of decking or fencing. But, it’s only meant for use on bare wood—it’s not designed for cleaning painted or stained wood. And we didn’t care for the scent, either. It’s not overwhelming, but we did detect a slightly acrid odor.
Get the Zep Wood Deck and Fence pressure washer soap at Amazon, The Home Depot, or Walmart.
Best for Siding
Krud Kutter House and Siding Pressure Washer Soap
Our Ratings: Ease of Use 4.5/5; Effectiveness 3.5/5; Scent 4/5; Value 4.25/5
Product Specs
- Type: Concentrated
- Surfaces: Siding
- Biodegradable: Yes
Pros
- Highly effective for removing mold, mildew, grime, and dinge from siding
- Cleans and brightens siding, leaving it looking fresh and new
- Biodegradable, so it’s not hazardous to use around landscaping and pets
Cons
- Solution shouldn’t be allowed to dry on the siding, so cleaning and rinsing may take longer
Accumulated dust, moss, and mildew growth can make a home’s siding look dingy and dated. Fortunately, Krud Kutter, a Rust-Oleum product, helps strip away dinge and grime, leaving the siding looking fresh and new again.
We poured it into the reservoir of our pressure washer and used it to clean two types of siding: cement fiber and stucco. We specifically targeted areas with deep dirt and what looked like the start of mildew growth. The soap did a great job of removing the mildew stains and dirt and left the cement-fiber siding looking great. It cleaned away all the stains on the stucco siding except for some cottonwood bud stains; those took some extra scrubbing.
This is a powerful cleaner, but it shouldn’t be allowed to dry on the siding. The manufacturer suggests cleaning small areas, 3 to 5 square feet at a time, and then rinsing thoroughly, For this reason, it took a little longer than other soaps we tested.
Because this formulation is biodegradable, it won’t damage landscaping or present a hazard to pets in the yard. It can also be diluted and used with a brush if desired. The concentrated formula makes up to 11 gallons of cleaning solution, which is enough to clean up to 3,200 square feet of surface area.
Get the Krud Kutter pressure washer soap at Amazon, Lowe’s, or Walmart.
Best for Driveways
Simple Green Oxy Solve Concrete and Driveway Cleaner
Our Ratings: Ease of Use 4.5/5; Effectiveness 4.5/5; Scent 4.5/5; Value 5/5
Product Specs
- Type: Concentrated
- Surfaces: Porous masonry surfaces
- Biodegradable: Yes
Pros
- Efficient at cleaning away dirt, rust, and other stains from masonry surfaces
- Eco-friendly and biodegradable: meets the criteria for the EPA’s Safer Choice Program
- Suitable for use on a wide variety of masonry surfaces
Cons
- May not completely remove heavy oil or grease stains without additional scrubbing
The second Simple Green Oxy Solve solution to earn a spot in our lineup, this product is formulated to clean porous masonry surfaces. It is also eco-friendly and meets the strict criteria for the EPA’s Safer Choice Program.
We tested the concrete and driveway cleaner on our driveway, a stucco wall, and a brick landscaping border. On all three surfaces, it did a good job of powering away dirt and light rust stains, but it wasn’t powerful enough to cut some old grease stains on the driveway. Still, we felt it was a high-quality cleaning solution. We didn’t notice any undesirable scent, but the solution did leave some bubbles behind that we had to rinse away with plain water.
The concentrated 1-gallon bottle can create up to 21 gallons of cleaner, which is plenty of fluid for cleaning a large driveway several times. In addition to driveways, it’s suitable for patios, pavers, and sidewalks. And since it’s biodegradable, there’s little need to worry about the cleaner damaging the lawn or landscaping.
Get the Simple Green Concrete and Driveway pressure washer soap at Amazon, Lowe’s, or Walmart.
Also Consider
Zep All-In-1 Premium Pressure Wash Cleaner
Our Ratings: Ease of Use 4.5/5; Effectiveness 5/5; Scent 4/5; Value 4.75/5
Product Specs
- Type: Concentrated
- Surfaces: All-purpose
- Biodegradable: No
Pros
- Suitable for a wide variety of surfaces and materials
- Suitable for large spaces; 1 gallon of concentrate can create up to 28 gallons of cleaner
- Affordably priced relative to more costly pressure washer soaps
Cons
- Scrubbing may be required for tougher stains
- Unlike most of the options on this list, this one isn’t biodegradable
This all-in-one pressure washer cleaner from Zep is ideal for cleaning a broad range of surfaces, including vinyl, wood, brick, masonry, metals, and plastics. We tested the cleaner on a concrete sidewalk, a truck, and cast-aluminum patio furniture.
It did a great job of cleaning away ground-in dirt and grime on our driveway, and it even brightened up an area with light rust stains. It came close to removing grease stains, but we could still see faint stains after we had finished. We cleaned the truck using our power washer’s foaming attachment, but the Zep solution didn’t produce as much foam as we would have liked. Still, it dissolved road grime from the vehicle’s underside and dried-on mud splatters, leaving the truck’s surface nice and clean.
It also did a good job of cleaning the cast-aluminum patio furniture, which had a winter’s worth of dried bird droppings to remove.
A 1-gallon bottle of this all-purpose soap is enough to make up to 28 gallons of cleaner. Be sure to spray down surrounding landscaping and plants before and after use.
Get the Zep All-In-1 pressure washer soap at Amazon, Ace Hardware, or The Home Depot (64 ounces).
Jump to Our Top Picks
What to Consider When Choosing a Pressure Washer Soap
Understanding how a pressure washer soap’s ingredients impact its cleaning ability is crucial when you’re shopping for the right cleaner. Learn more about this and other attributes of the best pressure washer soaps below.
Intended Use
When selecting the best detergent for a pressure washer, consider how you plan to use it. All-purpose pressure washer soaps work on most outdoor surfaces and are specially formulated cleaners for surfaces like pavement, siding, metal, and wood decking. If you plan to use a pressure washer to clean a variety of surfaces, use an all-purpose cleaner. On the flip side, if you want the best pressure washer detergent for cleaning a house, car, or driveway, look for one specially formulated for that purpose to achieve the best possible results.
Ingredients
Since pressure washer soaps are used to clean large areas such as entire home exteriors, driveways, and decks, much of the solution will end up draining into the surrounding yard and landscaping. With that in mind, it’s crucial to select a product with environmentally friendly ingredients. The most eco-friendly picks will not harm surrounding landscaping or be toxic to wildlife and pets.
Most pressure washer soap manufacturers prominently display on the label whether the product is biodegradable. A pressure washer soap sold on Amazon may also receive the online retailer’s Climate Pledge Friendly certification, indicating that it is eco-friendly.
Water Temperature and Type
There are pressure washer soaps for both cold water and hot water. Cold-water pressure washer soaps are the most common for residential cleaning. They’re easy to use and don’t require that water maintains a high temperature during the cleaning process.
Hot-water pressure washers are designed for industrial-strength cleaning that involves cutting through layers of grease and oil. Since they use heat, they are capable of killing bacteria and algae. Hot-water cleaners are more expensive but require less cleaning fluid to get the job done. However, they use more energy since the pressure washer must use heating coils to warm the water.
Concentrated vs. Diluted
Pressure washer soap comes in both concentrated and diluted solutions. Diluted solutions are already mixed with water and can be added directly to the pressure washer from the bottle, making them convenient to use.
Concentrated solutions must be diluted with water before adding them to the pressure washer’s detergent tank. Since the fluid is concentrated, a single gallon of concentrate can typically yield as much as 20 gallons of cleaner, making it much more economical than soap that has already been diluted. These concentrated options are often some of the best pressure washer solutions, especially for those who use a pressure washer regularly.
Most pressure washer soaps are concentrated, but they can be added directly to the machine’s soap reservoir, where they are automatically diluted with water. Alternatively, many can be manually diluted in a large bucket at a ratio of about 1 part soap to 20 parts water and sponged or brushed on the surface to be cleaned.
FAQs
If you’re wondering how to load soap into a pressure washer or whether you can use any type of soap in one of these cleaning machines, read on for answers.
The terms are often used interchangeably. Pressure washer soap is specifically formulated for use in a pressure washer, whereas detergent is a generic term for various types of cleaners, including pressure washer soaps.
For best results, use a soap specifically formulated for pressure washers.
You should not use just any type of soap in your pressure washer. Using a soap not specifically designed for a pressure washer could damage the machine.
Sun Joe’s pressure washer soap, which is biodegradable and can be used on various surfaces, is an ideal soap to use with a pressure washer, but any of the options we highlighted can work well, depending on your use case.
Locate the detergent tank on the pressure washer and add the pressure washer soap to it. Then, adjust the dial near the tank to the proper mix ratio for the soap and water needed for the job. Some pressure washers don’t have soap reservoirs, and in that case, you may need to dilute the solution in a large bucket and run a separate hose to the bucket to feed the solution through the washer.
Meet the Tester
Glenda Taylor is a product tester and writer specializing in the construction, remodeling, and real estate industries. She and her husband own a general contracting company, and Taylor is experienced in residential and commercial building applications. She tests a wide range of power tools and other home improvement, household, and lawn-and-garden products.
Additional research provided by Tony Carrick.
