I am part owner of an apartment building that received 15 feet of Gulf waters during a hurricane. Cast iron pipes were used and are visible on the first level garages. Plumbing is a common element, not individual to each apartment. Many sections were torn or broken away during the storm winds/flood. The cast iron pipes were submerged in the water for a number of weeks. The pipes/plumbing have not been used in 11 months. Inspection reveals a substantial amount of rust. The plumbing system was installed 25 years ago. We have received flood insurance money (maximum). At this time all units (24) are open and not occupied and debris has been removed. Is this the time to make a change or patch the system?