This section of the directory lists those drinking water treatment units which have been WQA certified in accordance with "Voluntary Industry Standard For Drinking Water Treatment Units--Aesthetic Effects," NSF/ANSI 42, 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 drinking water treatment units 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 reduction of specific aesthetic-related contaminants in drinking water. In addition, the materials and components used in these certified drinking water treatment units have met the rigorous safety and structural integrity and strength requirements set by industry Standard NSF/ANSI 42.

Replacement Components for a system may or may not reduce all reduction claims that system makes. Verify through literature what contaminant(s) each replacement component reduces. Note that replacement component(s) may be required for system to operate properly even though that same replacement component may not reduce contaminants for claims made under this standard.

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.