What Chemicals to Use When Pressure Washing Concrete

Using a cleaning solution enhances the results of pressure washing concrete. It helps loosen grime and kill growth. The right chemical can even lift stains you thought were set for life.

However, the wrong solution can damage concrete. Worse, it can harm the environment and even the user when mishandled. Today, Window Hero shares what chemicals to use when pressure washing concrete, important safety information, and other tips for revitalizing your patio, walkway, or driveway.

The best pressure washing chemicals for concrete

Choosing the best pressure washing chemical for your concrete is dependent on what you need to remove.

This is not an exhaustive list, but it’s a good quick-start guide to common cleansers and their most important uses.



Detergents for cleaning concrete can range from formulas designed for concrete to regular household dish soap.

These soaps are surfactants that can mix with water and bind to dirt, dislodging it. Most are environmentally friendly and don’t require any protective gear (gloves, goggles) to handle.

The catch is that they’re not the toughest solution for set-in oil stains, paint spills, algae, and more. You can increase efficacy by pre-treating with a stiff scrub brush and following it up with pressure washing.

A detergent is a good option for staying on top of concrete maintenance. Scrubbing concrete with plain soap and water as needed can decrease the frequency of using the tougher stuff.

Bottom line:
Least likely to cause damage or irritation Not as effective on serious grime or stains
Easy to find and use Best for regular maintenance
Environmentally safe


Citric acid

Citric acid is a top pick for homeowners who want a deeper clean but are wary of handling unfamiliar chemicals.

It’s biodegradable and found in many cleansers targeting wood decking, concrete patios, and driveways. It’s pretty effective on rust but is also a solution for efflorescence, that powdery white coating that can crop up on concrete.

Like a few other common acids, citric acid can etch concrete. Etching concrete increases the porosity of the surface. That’s a plus if you’re planning on re-sealing concrete after cleaning. If not, it can eventually lead to cracks.

If citric acid does not work on the degree of efflorescence you’re dealing with, talk to a pro about oxalic acid. It’s a stronger alternative.

Bottom line:
Less hazardous than other acids Slower-acting than other acids
Biodegradable Etches concrete; should seal afterward
Good for efflorescence


Enzyme-based cleaners

Enzymatic cleaners are a biodegradable, non-harmful way to rid concrete of organic matter. Think pet stains, bird droppings, and oil spills. With these, good bacteria create enzymes that eat away at stains and soil.

You should consider enzyme cleaners if odors are a concern. They are also safe if you’re worried about using chemicals in places pets and kids frequent.

Be advised that enzymes won’t be effective on inorganic matter such as mineral deposits. It’s also important to read the instructions on the product. Removing oil stains may require a different application method than removing bird waste, for instance.

Bottom line:
Safe and non-irritating Less effective on old and inorganic stains
Natural and biodegradable Different stains require different methods
Ideal for organic matter Doesn’t work on mineral deposits


Sodium hydroxide

Sodium hydroxide is an alkaline cleaner that’s good for degreasing. Also identified as lye and caustic soda, this is where you begin to tread into territory requiring additional caution.

However, it is a mainstay and a must-have in pressure washing. It’s highly effective for dirt, grease, and other types of buildup that come from letting concrete maintenance go.

Sodium hydroxide is another cleaner that should be followed up with a sealant. It’s suitable for routine use but can increase the porosity of concrete surfaces.

Professionals and other experienced users will know how to handle sodium hydroxide to mitigate potential harm to humans and the environment.

Bottom line:
Strong degreaser Better left to professionals
Cost-effective Can cause irritation
Good for routine use Can etch; seal concrete after using


Quaternary ammonium compounds

Humid environments or poor drainage can lead to excessive algae, mildew, mold, and other types of growth that threaten the integrity of concrete. For this, consider quaternary ammonium compounds, also known as quats.

Quats are a type of antimicrobial disinfectant. They are an effective algaecide that can eradicate growth and preserve concrete.

Note that as an antimicrobial, quaternary ammonium compounds are also considered a pesticide. Read the packaging carefully for instructions about storage, use, exposure, and disposal. Better yet, consult a professional pressure washing company.

Ideal for mildew, mold, algae May not work for every type of stain
Less corrosive than bleach Can cause irritation


Safety tips for using chemicals on concrete

Here are the precautions to take if you plan on using chemicals to pressure wash concrete yourself:

  • Read instructions: Follow all manufacturer safety guidelines.
  • Diluting: Always double-check to see if your product needs to be diluted and stick to the recommended ratios.
  • Patch test: When in doubt, apply a bit of the solution to a small, inconspicuous patch of concrete.
  • Rinse: Cleaning solutions should be thoroughly rinsed off the concrete. Avoid rinsing chemicals into areas with poor drainage or leading toward a water supply.

What do you spray on a driveway before pressure washing?

Before pressure washing, you can spray a driveway with soapy water, diluted vinegar, or a dedicated driveway cleaning spray. Some homeowners may use diluted bleach to tackle mildew, but this can be a threat to adjacent grass and other plant life. The right chemicals ensure you can pressure wash your driveway in a timely manner.

Use a brush to work the cleanser into tire marks and stains before using the pressure washer.

When in doubt, ask a professional

Window Hero takes the guesswork out of knowing what chemical to use when pressure washing concrete.

We speak with you one-on-one about your concrete and come to your home or business. After choosing the right cleaning solution for the job, we use professional-grade equipment to get the deepest clean possible.

It’s safe, reliable, and yields brilliant results. Contact us today to book your appointment.

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