Haw. Rev. Stat. § 481H-3

No water treatment unit that claims to reduce or eliminate the concentration of one or more health related contaminants in water supplies intended for human consumption may be sold or leased, offered for sale or lease, distributed, or installed in the State unless the unit has been tested using industry accepted product testing protocols or protocols that utilize technically valid methodology using United States Environmental Protection Agency analytical testing methods for drinking water quality and maximum contaminant levels, or their equivalent.