Hot Water Pressure Washing
Hot water pressure washing uses a diesel-fired burner to heat the pressure washer's output to 180-200°F before it hits the surface. The physics is simple: hot water dissolves grease and oil, accelerates chemical reactions, lowers the dwell time needed for detergent to work, and kills biological growth on contact. Cold-water pressure washing relies on mechanical force and chemistry alone, which means longer jobs and lower performance on greasy substrates.
In depth
For automotive oil stains, restaurant hood grease, dumpster pads, gum removal, and heavy commercial cleaning, hot water is not optional — it is the only method that produces a genuinely clean result in a reasonable time. For residential work (siding, driveways, decks) cold water is almost always sufficient because the contaminants are organic and biological, not petrochemical. The tradeoff is weight, fuel cost, and complexity: hot-water skids are heavier, require diesel, and have more moving parts that can fail. A full-service commercial-capable operator carries both.
How this shows up on our jobs
Our commercial rig includes a hot-water skid for oil-stain removal, gum removal, dumpster pads, and restaurant grease — jobs where cold water simply will not cut it.
Services where this matters
Related terms
PSI (Pounds per Square Inch)
PSI is the unit of pressure used to rate pressure washers, measuring the force of water exiting the pump per square inch of surface area. Consumer pressure washers run 1,500-2,500 PSI; professional rigs typically produce 3,500-5,000 PSI; and specialty surface cleaners can spike above 8,000 PSI. Higher PSI is not always better — in fact, for most home exterior surfaces, high PSI is destructive. Vinyl siding, wood shingles, soft mortar, roof granules, and painted surfaces all fail under excessive pressure.
GPM (Gallons per Minute)
GPM stands for Gallons Per Minute — the volume of water a pressure washer delivers per minute of operation. While PSI gets the headlines, GPM is what actually does the cleaning. Think of it this way: PSI is the hammer's strength; GPM is how many hammers you're swinging. Higher GPM means more water flowing across the surface, which means faster dirt removal, better rinsing of detergents, and shorter job times.
Surface Cleaner
A surface cleaner is a circular attachment — typically 16, 20, or 24 inches in diameter — that replaces the wand on a pressure washer for cleaning flat horizontal surfaces. Inside the housing, two or four high-pressure nozzles spin on a swivel bar, blasting the surface at a consistent angle and distance while a skirt contains the spray. The result: an even, streak-free clean across a driveway, patio, or sidewalk in a fraction of the time a wand would take — and without the wand-streak "zebra stripes" that plague amateurs.
Dwell Time
Dwell time is the interval between applying a cleaning chemistry to a surface and rinsing it off. It is the single most misunderstood variable in exterior cleaning. Chemistry does not clean instantly; it needs time to break chemical bonds, kill organisms, or dissolve minerals. Too little dwell and the chemistry is wasted. Too much dwell — especially in direct sun — and the chemistry can damage the surface, bleach landscaping, or drive the stain deeper.
Alkaline Cleaner
An alkaline cleaner is a high-pH detergent (typically pH 10-14) that dissolves oil, grease, fats, protein stains, and atmospheric grime by saponifying fatty acids and emulsifying petrochemical contaminants. The most common alkaline ingredients in exterior cleaning are sodium hydroxide (caustic soda), sodium metasilicate, and potassium hydroxide, often combined with surfactants, chelators, and dye. Alkaline cleaners are the counterpart to acid cleaners — pros reach for alkaline chemistry when the stain is organic or petrochemical, and acid when the stain is mineral.