Tandem water softening units are designed for the establishments needing soft water 24 hour continuously.as well as the systems with flow control, there are products able to make backwashing accordin to the hardness of the water. In tandem's systems, because the regeneration is done at the proper time, the resin corrosion and overconsumption of the salt is prevented. In the systems over 50 m3\hour flow, the diaphragm valva groups and galvanic tanks able to work in hydraulic and pneumatic way are used.