The AWSS remains the only high- pressure network of its type in the United States, and was the only public project funded by the citizenry following the Great Earthquake of 1906. Strongly influenced by the insurance companies of the period, the AWSS is dedicated to the principle that the City will never again be destroyed by fire, at least not for lack of water for fire fighting purposes. The AWSS system utilizes San Francisco's hilly terrain and waterfront perimeter to the best advantage with an excellent combination of features. The structure and design of each component illustrates how the design engineers aimed to defeat the devastating results of earthquake and fire. This reservoir, constructed of reinforced- concrete slabs six inches thick, is divided into two equal bays.
Normal discharge flows from one bay only.
In the event of a sudden break in the pipeline distribution system, only one- half of the capacity would be lost. Saltwater has better fire- extinguishing properties, but it is more destructive to fire fighting equipment. It has gated manifold connections to the Twin Peaks Reservoir, but is only supplied with the higher pressure when required. This tank is staffed 24 hours per day, and has normally closed, gated manifold connections to the Ashbury distributing system. When required, the reservoirs can be interconnected to provide a total static pressure of 325 psi on the high- value congested downtown districts.