The working principle of an electric pressure washer is – first detergent is added to the spray bottle and cold water is filled into the tank. When the machine is switched on, the electric motor starts working. The water pump draws water and detergent and mixes them together. Some of the pressure washers have the capability of controlling the temperature of water mixture (i.e at 50 ˚C – 70 ˚C). when you trigger the gun, water is ejected through the nozzle. You can set the pressure level as per the requirement before switching the machine on.