Property owner may request for x-rays before coring the floor slab, it's an additional cost. Most Stratas and newer buildings insist on it.
I understand about the HD's concerns about an "air gap", what 'They" (HD) are concerned about is the event of a sewer back-up: Contaminated water will enter the sink and/or ice machine and contaminate everything in it. Fair enough, but the intelligent thing to do, and what they do around here (BC Canada) is insist on a back-up prevention device on each sink or ice machine. It's just a simple one-way valve hooked up to each sink/ice machine drain.
It's my understanding that California has some pretty wierd and stupid laws about "air gaps" and all that, while totally ignoring one-way valves.