Any existing backflow preventer assembly shall be allowed by the Water Purveyor to continue in service unless the degree of hazard is such as to supersede the effectiveness of the present backflow preventer assembly, or there is an unreasonable risk to the public health. Where the degree of hazard has increased, as in the case of a residential installation converting to a business establishment, any existing backflow preventer assemblies must be upgraded to a reduced pressure principle assembly, or a reduced pressure principle assembly must be installed in the event that no backflow preventer assembly is present.
(1-18-05)