Page 104 - Water Loss Control

86 Cha pte r Se v e n

60

50
UARL (gal/mi of mains/d/psi) 40 Meter 100 ft after
curb stop

30

20
Service lines,
main to curb stop
10
Mains
0
0 20 40 60 80 100 120 140 160 180 200
Density of service lines (service lines/mi of mains)
FIGURE 7.2 Unavoidable annual real losses (Gal/mile of mains/day/psi ) vs. density of service
connections. (Source: Ref. 7.)

Comparison of IWA system–specific values of unavoidable annual real losses in gallons
per mile of mains per day compare well with the range of 1000 to 3000 gal/mi/d usually
quoted for North American systems. However, the IWA prediction method has the consider-
able advantage that it allows estimates to be made on a system-specific basis, taking account
of density of connections, average operating pressure, and locations of customer meters (rela-
tive to the curb stop). The last of these factors is particularly important in a region of diverse
climates such as North America, where some customer meters are close to the curb stop and
others are in buildings more distant from the curb stop.

0.7

0.6
UARL (gal/service line/d/psi) 0.4 Meter 100 ft after
0.5

0.3
curb stop
0.2
Service lines, main
0.1 to curb stop
Mains
0.0
0 20 40 60 80 100 120 140 160 180 200
Density of service lines (service lines/mi of mains)

FIGURE 7.3 Unavoidable annual real losses (gal/Service Line/d/psi ) vs. density of service lines.
(Source: Ref. 7.)