This section of the directory lists those water softeners which have been WQA certified in accordance with "Voluntary Industry Standard For Household and Commercial Cation Exchange Water Softeners," NSF/ANSI 44, and is published periodically by the Water Quality Association (WQA), as a service to the industry and consumers. The WQA is a not-for-profit international association of manufacturers, distributors, and dealers of water treatment systems for household, commercial, and industrial applications. This online directory is continuously updated to identify those water treatment equipment products that have been tested and passed stringent industry standards to become certified by the Water Quality Association.

Certification means that a production model of the listed line of water softener was tested at the Water Quality Association laboratory, or any of the other testing laboratories recognized by the Water Quality Association, and was found to have met the standards for removal of hardness and reduction of specific contaminants. In addition, the materials and components used in these certified water softeners have met the rigorous safety and structural integrity and strength requirements set by industry Standard NSF/ANSI 44.

Stand-alone components certified for materials safety and structural integrity (as applicable) requirements only may also have notes indicating that the component has been tested for the reduction of specific contaminants. Because components certified only for materials safety and structural requirements are incapable of functioning without the use of additional components or by being placed into a complete system, performance reduction claims listed as a note are for informational purposes, shall not be considered certified, and may not perform exactly as stated when placed into a system.