Figure 2-19.—Typical distribution system layout.
3. STORAGE RESERVOIRS. Storage reservoirs
are structures used to store water. They also equalize the
supply or pressure in the distribution system. A common
example of a storage reservoir is an aboveground water
storage tank.
4. SYSTEM ACCESSORIES. System accessories
include the following:
a. BOOSTER STATIONS. Booster stations are
used to increase water pressure from storage tanks or
low-pressure mains.
b. VALVES. Valves control the flow of water
in the distribution system by isolating areas for repair or
by regulating system flow or pressure.
c. HYDRANTS. Hydrants are designed to
allow water from the distribution system to be used for
fire-fighting purposes.
d. METERS. Meters record the flow of water
in a part of the distribution system.
e. SERVICE CONNECTIONS. Service
connections are used to connect individual buildings or
other plumbing systems to the distribution system
m a i n s.
f. BACKFLOW PREVENTERS. A cross-
connection is any connection between a potable and
nonpotable water system through which a
contaminating flow can occur. Backflow preventers,
such as air gaps and vacuum breakers, are used to
prevent flow through potential cross-connections.
DISTRIBUTION SYSTEM LAYOUT
When distribution systems are carefully planned,
the pipes are usually laid out in a grid or belt system. A
network of large pipes divides the community or base
into areas of several blocks each (fig. 2-19). The streets
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