15.100.140   Secondary supply.
   In addition to the main water supply, a secondary on-site supply of water equal to the hydraulically calculated sprinkler design demand plus one hundred (100) gallons per minute additional for the total standpipe system shall be provided. This supply shall be automatically available and shall have a minimum duration of thirty (30) minutes. A fill device shall be installed to automatically maintain the required water supply.
   A.   Open type reservoirs, pools, fountains, or wells shall not be used as the on-site water supply.
   B.   Only approved corrosion resistant type tanks shall be permitted.
   C.   The on-site water supply shall be provided with a low level indicator and shall be interconnected to the life safety control panel. The low water level indicator shall be a separate zone and shall transmit a trouble signal only, when the total volume has been reduced to the minimum required amount.
   D.   Locations of auxiliary water tanks and controls shall be approved by the authority having jurisdiction. (Prior code §§ 9.28.1213, 15.09.902)