I feel the language of this Section pertaining to the mandatory installation of a backflow prevention assembly, or backflow elimination method, in instances of building height of at least four (4) stories, needs to be simplified.  A slight modification of the current verbiage of 610.E.20 would not only be adequate, but less complicated and thus less confusing. 

A structure of four (4) or more stories above grade, whether multi-story office or other commercial buildings, or whether adjoining townhomes, duplexes or free-standing residences, all present the same issue and potential hazard to the municipal water supply. The hydraulics of downward force generated by water at this height does not distinguish between whether this water is contained within a commercial or residential building. It is unimportant whether the lowest level is an above-ground garage or the first floor of the residence or commercial building, and it is equally unimportant whether the 4th level is referred to as a "habitable space" less than 750 square feet if this space is plumbed to serve a bathroom and/or a wet bar.  

My recommended wording for this Section is as follows: "Buildings, whether commercial or residential, and whether adjoined or free-standing, that are four (4) or more stories above the water meter serving the building".