Replacing Galvanized Water Lines

Happy Thanksgiving to everyone! We are looking to buy an older city park. In our due diligence we have found out that there have been many water leaks at this park. The owner believes that the water lines are galvanized and thnks they are very old. Water is from the city. We were told that the lines are not under the paved street and farely easy to get to. What type of company should we hire to get more information about this problem? Is it a water leak detection company or can you just use a regular plumber? Also how costly is it to replace a galvanized line system. The parks is your typical city park, that has one road with (46) units along it. Thanks everyone for your help.