Water temperature has a significant affect on cleaning performance. As the temperature of the water increases so does the cleaning performance. Hot water will clean grease and grime far better than cold water will even when using cleaning compounds. However excessive water temperatures should be avoided since these can increase the risk of injury to operators and may damage surfaces. Most positive displacement pumps cannot handle very high water temperatures (over 130°F) and a heater to heat the water after it discharges the pump should be used if higher temperatures are desired. Normally if any significant amount of washing will be done a domestic water heater such as the one in your home will not be sufficient to supply the demand of a pressure washer.