There are other codes used for fire water tanks- notably NFPA-22.
Water tanks are normally lined.
There will normally be some differences in the appurtenances.
There are regulatory differences in location, diking, etc.
Hi gent! Thanks for the help. Called up a local supplier and he was able to answer some of the questions, in addition to the what you all said. The type of seal is different. Also mentioned that optional certification are different for the tanks.