This paper outlines Ontario Clean Water Agency's (OCWA) experience in registering a major water system under ISO 14001. OCWA's certified registrar, SGS International Certification Services, audited the facility to ensure that these requirements were met: that the facility understands all the environmental aspects and related impacts and is acting to address them; that the facility understands and is meeting all legal requriements, bylaws, and industry standards; and, that the facility can demonstrate that the environmental management system is continually improving. To remain registered, OCWA will be audited annually by a certified registrar. The step-by-step registration includes: establishing an environmental policy; planning; implementation and operation; checking and corrective action; and, management review. The OCWA's web site is given for more information.