This OneFlow^® anti-scale system OFTWH, provides protection from scale formation on internal and external plumbing surfaces. It is a single cartridge-based system that must be installed on a cold water line prior to a water heating device for single tankless heaters. It prevents scale by transforming dissolved hardened minerals into harmless, inactive microscopic crystal particles that stay suspended in the water then are passed to the drain. This 6 GPM system consists of a single cartridge within a filter housing that has a standard 3/4 inch female NPT connection and should be plumbed with a bypass valve to allow isolation of the filter housing. The cartridge should be replaced at least once every two years for effective scale treatment. The OneFlow ^® media has been tested and certified for material safety to NSF/ANSI Standard 42 and 61.