For mobile cleaning applications, pressure washers may be directly fed from a tank without using a pump to push the water from the vessel to the machine. However, direct drive pressure washers must be kept close to the tank and will be less likely to cavitate if the machine is below the tank level. Belt drive and gear drive machines are capable of pulling from a tank even more effectively and can be located slightly higher than the water source. Its always best to locate the pressure washer as close to the water source as possible and lengthen the high pressure hose to reach the cleaning location.
While we have seen a few customers have success using a pump to supply their pressure washer from a tank, it doesn’t happen often and we do not recommend using that type of system. In many cases, supply pumps have a fluctuation in their flow rate and this makes them prone to gravitating the high pressure pump. Turbulence in the inlet flow on the pressure washer causes cavitation just like starving the pump or introducing air into the inlet stream. As a result of this, we neither recommend nor sell equipment for pumping water from a tank to a pressure washer without having an additional reservoir or tank for water right at the machine.