Soft washing vs. pressure washing

April 10, 2023

Elerein Yanki

Hi, I am Yanki, the founder of bisonclean.com. I have been in the cleaning equipment field for more than 5 years now, and the purpose of this article is to share with you the knowledge related to cleaning equipment from a Chinese supplier's perspective.

In the world of exterior cleaning, two methods dominate the field: soft washing and pressure washing. Both have their unique strengths and applications, making them invaluable tools in maintaining cleanliness and aesthetics. This blog aims to provide an in-depth comparison of these two methods to help you make informed decisions.

This soft washing vs pressure washing comparison helps you make informed decisions about surface type, contamination severity, and long-term maintenance needs.

What is soft washing?

Soft washing is a cleaning method used to remove dirt, algae, mold, mildew, and other contaminants from surfaces such as roofs, siding, decks, and fences, including algae removal from porous surfaces. Unlike pressure washing, which uses high-pressure water to forcefully clean surfaces, soft washing utilizes low-pressure water combined with specialized cleaning solutions and is particularly effective for delicate surfaces or areas where high-pressure cleaning could cause damage.

Soft washing is different from pressure washing, which uses high-pressure water—up to 4,000 PSI—to physically blast away dirt and grime. Soft washing is a more gentle approach that stays well under 500 PSI and focuses on chemical treatment, relying on the cleaning solution’s properties to effectively clean the surfaces. This fundamental gap in operating pressure is exactly why the two methods suit different surface types: soft washing is meant for delicate materials that can’t withstand forceful impact, while pressure washing is reserved for tougher, more resilient surfaces.

Soft washing uses a pump sprayer with water spray and chemicals to effectively clean exterior surfaces, with nozzle attachments that facilitate precise application. The typical pressure for soft washing is between 150-300 PSI, comfortably within the sub-500 PSI range that defines this gentler category.

The use of low-pressure water and specialized cleaning solutions ensures a thorough and gentle cleaning process.

The soft washing process typically involves the following steps:

Inspection: The surface to be cleaned is inspected to identify the type and extent of contamination and determine the appropriate cleaning solution.
Pre-treatment: A biodegradable cleaning solution is applied to the surface. This solution is usually a blend of water, detergents, and chemicals specifically formulated to kill and remove organic growth and stains.
Dwell time: The cleaning solution is left on the surface for a specific period (dwell time) to allow it to penetrate and break down the contaminants.
Low-pressure rinse: After the dwell time, the surface is rinsed using low-pressure water, typically from a garden hose or a specialized soft washing system. The low-pressure rinse removes the cleaning solution along with the loosened dirt and contaminants.

For information on using a pressure washer, please refer to “How to do soft washing with a pressure washer.“

Soft washing can be used to remove the following stains or buildup:

Mold, mildew and fungi
moss and weeds
algae and bacteria
grease
Wildlife debris
rust
organic matters

Soft washing benefits:

Safety: Since it uses low pressure, soft washing minimizes the risk of damaging delicate surfaces like vinyl siding, aged wood, and shingles.
Effective deep cleaning: Cleaning solutions penetrate deeply, eliminating organisms at their roots.
Long-lasting results: By killing organisms down to the root, soft washing ensures the cleaned areas stay clean for longer

What is pressure washing?

Pressure washing, or power washing, uses high-pressure water jets between 1,300 and 2,800 PSI to clean exterior surfaces. Pressure washing can remove many of the same stains and buildup as soft cleaning, including loose paint, mold, mud, dust, dirt, and grime. However, it usually does so without the help of chemicals, instead relying on water pressure to get the job done.

The power of pressure washing cannot be underestimated. Pressure-washing surfaces intended for soft washing poses a risk of damage. Mortar or grout can be removed from between bricks or tiles. Bitumen can be removed when cleaning the roof. Water damage can also occur when water under high pressure is inadvertently forced under a home’s siding. In all, caution must be exercised when pressure washing delicate materials or surfaces to avoid causing damage.

Therefore, pressure washing works best on stone, garage floors, asphalt driveways, sidewalks, treated wood decks, stucco, and patios.

The process of pressure washing typically involves the following steps:

Preparation: Remove obstacles, loose debris, or delicate items that could be damaged by high-pressure water.
Equipment setup: Connect the pressure washer to a water source. Depending on the type of pressure washer, it may be powered by electricity, gasoline, or diesel.
Nozzle selection: Select the appropriate nozzle based on surface type and cleaning level required; different nozzles produce different spray patterns and pressures.
Application: Direct the high-pressure water jet at the surface using sweeping motions to ensure even coverage. The water force dislodges and removes dirt, grime, and contaminants.
Optional detergents: Apply pressure-washing-specific detergents or cleaning solutions before washing to enhance cleaning and help break down tough stains.
Rinse: Thoroughly rinse the surface with water to remove remaining detergent or loosened debris.

Pressure washing benefits:

Speed: Pressure washing covers 2,000 sq.ft. of driveway in 30–45 minutes — 2–3× faster than soft washing on the same area.
No chemical dependency: High-pressure water alone removes loose paint, mud, grease, and heavy grime without dwell time or chemical cost.
Versatility: With interchangeable nozzles (0°–40°), one pressure washer handles everything from stripping paint (0°) to rinsing patios (40°), simply by changing the tip and standoff distance.

When to avoid pressure/power Washing

Now that you understand the difference between pressure washing and soft washing and when to use each method, the next question is: when should you avoid them?

When should you not use pressure washing?

Pressure washing does use pressurized water at a specific PSI, depending on the surface, so background knowledge is recommended. Avoid pressure washing delicate surfaces such as roofs, siding, and painted or aged wood, since forceful water can strip finishes or force water underneath materials. Most professional electric washers know when to use the soft wash system versus when to use the heavy wash method.

Improper pressure washing can damage the finish! This means you should be careful to pressure wash decks and wood surfaces and never pressure wash the following:

Asphalt shingle roofs: The high-pressure jet strips protective granules and forces water beneath shingles, reducing roof lifespan by up to 50%. Always use soft washing (150–300 PSI) instead.
Siding (vinyl, wood, fiber cement): Water at >2,000 PSI can be driven behind panels, trapping moisture and causing rot, mold, and interior water damage.
Painted or aged wood: High-pressure water peels paint instantly and erodes wood fibers, leaving a rough, splintered surface.

Contrary to what you might think, pressure washing roofs can be highly damaging to asphalt shingles. Pressure washing a roof can damage and weaken shingles, leading to more significant problems.

When to avoid soft washing?

Do not soft wash colored concrete or hard surfaces without professional guidance. With soaps, chemicals, and detergents involved, specific solution concentrations matter for siding and roofs—consult a professional if unsure.

Watch for visible algae or moss streaks on roofing, rising cooling costs from heat-absorbing black stains, and dark blotches on siding—these signs indicate biological growth is damaging surfaces and warrant a wash sooner rather than later.

Conclusion

Soft washing and pressure washing each have their place in the cleaning industry. Understanding their differences and strengths will allow you to offer the best service to your clients, whether they need gentle cleaning or power washing.

Remember, the surface material, the size of the area to be cleaned, the available time, budget, experience of the operator, and the environmental impact are all factors that should guide your choice between soft washing and pressure washing.

Ready to get started with your pressure washing project? To achieve professional results, you need equipment that performs under pressure. As a trusted pressure washer manufacturer, Elerein delivers the high-performance pressure washers that professionals rely on. Partner with us today to provide your clients with the quality they demand and the reliability they deserve.

FAQs about soft washing vs. pressure washing

Is soft wash worth the money?

Soft washing costs more upfront than pressure washing, but delivers superior long-term value. Because soft washing kills organisms at their roots rather than just surface-blasting them away, cleaned areas stay clean significantly longer—reducing repeat jobs and maintenance frequency.

How much water does each method use?

Soft washing: 0.5–2 GPM. Pressure washing: 2–5 GPM. Soft washing uses up to 60% less water overall.