The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
How To Design And Install Plumbing
Disinfection. Before the filtered water is delivered to the city water mains it must be disinfected or sterilized. This is accomplished with the use of chlorine gas injected into the water supply. The exact reaction which occurs in this process is not definitely known, but it is believed that a chemical reaction between the chlorine and the remaining bacterial organisms occurs, a harmless chemical compound resulting therefrom.
Calcium and Magnesium Removal. The removal of calcium and magnesium salts on a large scale has not proved entirely practical. The process will be discussed in the chapter dealing with private water correction.
Public Water Distribution. The method of water distribution usually is determined by the source from which the supply of water is secured. Where the supply is taken from lakes or rivers, the direct method of distribution is used.
Direct Pressure Distribution. The direct pressure method of water distribution obtains its supply of water through a large diameter intake installed on the lake basin and extended into deep water. The intake in some instances is provided with a shaft, which is known as a "crib," to make it accessible. The inlet end of the intake is, as a rule, provided with a metal hood and is extended vertically from the bottom.
It is the usual practice to take the water from the lake to a receiving well by gravity, from which point it passes through the filtration plant by the same method or by means of pumping equipment. The filtered water is pumped from the storage reservoir by centrifugal or piston pumps into the city water mains under a degree of pressure sufficient to serve specific needs.
The pumping equipment used in the direct pressure method of water distribution operates continuously in order to maintain a constant pressure in the city water mains. The mains are constructed of cast-iron pipe and usually are laid in the street—on the north side of streets running east and west, and on the east side of streets running north and south. They are located about ten feet from the curb.
Water mains usually are cross connected with one another so that a constant movement of water is maintained. Thus the possibility of the water becoming stagnant is averted. Sections of the main are controlled with valves that are made accessible through stop boxes extended to street grade. By this means, parts of the system can be controlled in the event of a breakdown in the piping material.
The contour of the soil varies in many cities and it becomes necessary to use pressure equalizing stations in some locations. These stations consist of an overhead storage tank and booster pump to provide additional pressure to serve these high areas. The direct pressure system is a very practical one and may be adapted to places where the supply of water is inexhaustible.
