The pneumatically operated pump delivers clear water and increases the pressure by a factor of 1.6. The water is pumped into a storage tank. It is used in combination with a blasting agent to clean façades and historically important listed monuments. The pump’s automatic internal reversing system eliminates the need for additional control valves. The pumping frequency and pressure are set automatically based on the flow rate in the storage tank. Once the maximum pressure is reached, the pump stops and restarts automatically when the pressure drops.