Abstract: A method and apparatus are disclosed for providing a supply of fresh water during emergency situations when the normal fresh water source is interrupted and for generating a high volume of air-water foam for extinguishing fires. The emergency system is connected to the normal fresh water source at the place of installation and diverts the fresh water through a standby tank to continually replenish the tank with fresh water. In the event of fire, a regulated source of high pressure gas is supplied to the tank to expel the water at high pressure through a high expansion foam generator, the foam outlet of which communicates with the spaces of the building or other installation in which the system is installed. The standby tank of reserve water may be positioned above or below ground level according to alternate embodiments of the invention. Other embodiments are disclosed wherein a separate foam generating installation for extinguishing fires is adapted for use with one or more foam generators.