Determining max tank size for my apartment?

[MitchM]

Vagabond,
You should probably ask your insurance company and the landlord/owner.
City hall may have the plans on file to help determine the construction of the building.
Determine where in the apartment you want to put the tank, and which way the joists are running.

And if you feel like doing some calculating, here's a link for building code info:http://www.mcvicker.com/resguide/toc.htm

HTH,
Mitch