Through softening the calcium and magnesium salts in the water are exchanged for sodium salts that do not cause the disadvantages of hard water. The method is used in industries and institutions for treatment of water for steam boiler plants and district heating plants, laundries, cooling towers, rinse processes, washing, dishwashing etc. Plant description: Flow rates for standard modules: Up to 100 m³/h per unit. The plants are produced as one-tank plants and multi-tank plants as well as cold water plants and hot water plants. The filter tanks are of steel and coated with polyethylene. Each plant is supplied with a control unit adapted to the job. The plant can either be timer controlled or meter controlled. Meter control gives the best average water quality and economy. Advantages and references: The broad programme makes it possible to choose the optimum plant for the project whether the need is continuos or discontinuos water supply. Frame-mounted two-tank plants ensure a short installation time. The choice of materials and the simple and robust design of both plant and valve unit result in a long plant life, 25 years are not unusual.