It was suggested that I ask here.

Some residential properties in New York City still have galvanized pipes for the inlet water line. Since heavy metals from the galvanization can leach into the water, this kind of pipe is no longer specified as an allow building materials according to NYC plumbing code.

• § PC 605 does not specify an allowance for galvanized parts, in piping, fitting or joints.
• $ PC 605.3 has a table that does not specify galvanization as an allowed material. This is in context to [the containing] Section 6, which regards Water Supply and Distribution.
• § PC 702 does allow galvanization in drainage.
• All other usages in this doc deal with non-water systems, or non-inflows.

But in the plumbing code I cannot find a clause section for grandfathering existing galvanized piping.

• Does a grandfathing clause exist in a superseding city code or law?
• Where might I find the change in law that first disallowed galvanized pipes in this usage? (Wherein may also have been specified how to handle existing installations)