Which is better, hot water or cold water? Both have pros and cons. For most residential pressure washing in Middle Georgia, I use cold water. House washing and gutter cleaning with cold water is perfectly fine. Some people use warm water, but it's not necessary. Hot water should not be use on wood. Hot water is definitely needed when cleaning commercial sites like restaurants and parking lots. Hot water cuts through grease with very little or no use of chemicals, while cold water must be accompanied by chemicals. As far as oil, gas, diesel, transmission fluid, power steering fluid, etc., the use of degreasers and hot water will significantly improve the look of the substrate, though a shadow may still appear as the end result. Even though they CAN be removed with cold water, hot water is far superior removing gum spots.
The end result - For most residential applications, cold water pressure Washing is ok. For most commercial pressure washing in Middle Georgia, the use of hot water is needed.