All backflow prevention assemblies existing at the time the ordinance codified in this chapter is adopted, but which do not meet the requirements thereof, shall nonetheless be excluded from the requirements of this chapter; provided they were approved for the purposes described herein at the time of installation and have been properly maintained so as to function in the manner originally intended. Such previously existing assemblies nonetheless shall be subject to the periodic inspection and testing required by Section 13.20.030. Whenever an existing assembly is moved to another location, or requires more than minimum maintenance, or where it is determined to constitute a hazard to health, the unit shall be replaced by an approved backflow prevention assembly meeting the requirements of this chapter. (Ord. 91-02 § 6)