NOVELTY - System for treating, preferably analyzing and/or synthesizing of liquids, comprises a liquid unit with at least one functional unit, at least one first liquid storage (130), at least one second liquid storage, a first liquid line, which connects the first liquid storage and the liquid unit for conducting the liquid from the first liquid storage into the liquid unit, and a second liquid line, which connects the second liquid storage and the liquid unit for conducting the liquid from the liquid unit into the second liquid storage.    USE - The system is useful for the treatment of liquids, preferably for the analysis e.g. in process measurement or in industrial measurement, where the analysis system is useful for monitoring and optimizing the cleaning performance of a sewage treatment plant and monitoring quality of drinking water and food and for measuring and monitoring e.g. the content of a liquid sample in particular substances,e.g. ions as ammonium, phosphate or nitrates or biological or biochemical compounds e.g. hormones or microorganisms e.g. bacteria.    ADVANTAGE - The system is capable of performing continuous treatment without replacing parts in between. The system is robust, inexpensive and easy to use, preferably avoids operator risk and environmental risk.    DETAILED DESCRIPTION - System for treating, preferably analyzing and/or synthesizing of liquids, comprises a liquid unit with at least one functional unit, at least one first liquid storage (130), at least one second liquid storage, a first liquid line, which connects the first liquid storage and the liquid unit for conducting the liquid from the first liquid storage into the liquid unit, and a second liquid line, which connects the second liquid storage and the liquid unit for conducting the liquid from the liquid unit into the second liquid storage. A flow of liquid through the first liquid line in the direction from the liquid unit to the first liquid storage is at least temporarily blocked by means of a first valve. A flow of liquid through the second liquid line in the direction from the second liquid storage to the liquid unit is at least temporarily blocked by means of a second valve.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the system for treating liquids.    Stock cartridge (100)    Circuit points (110)    Shutter element (120)    Liquid storage (130)    Back-pressure valve (150)