The process is applicable to pharmaceutical water, chemical process water, medium-pressure boiler make-up water, biological chemical process water, medical and health care water, pure water for the electronics industry, cleaning and cooling water for the machinery industry, smelting water, civil pure water. The main configurations are raw water tank, raw water pump, mechanical filter, activated carbon filter, precision filter, dosing device, primary reverse osmosis host pump, primary reverse osmosis host, cleaning device, secondary dosing device, secondary reverse osmosis host pump, secondary reverse osmosis host, fresh water tank, freshwater pump, pure water tank, pure water pump, ultraviolet sterilizer, etc.