The bypass valve is used to regulate the hardness of treated water. The valve adds (softens) a small amount of untreated source water to the softened water.

A convenient handle ensures precise position fixation for smooth regulation. A scale is provided on the mounting unit housing for this purpose. The valve has four outlets: two from each control block, and the unused outlets are closed with plugs included in the kit.

In addition to its main purpose, the Runxin F70A bypass valve can also be used to bypass water to the softener. This allows for uninterrupted service.