Page 335 - Water Loss Control

304 Cha pte r Ei g h tee n

Direct pressure use Consumption after the reservoir
Leaks between the meter
and reservoir House

Affected by pressure
Not affected by pressure

Meter
Road

Service
Main

FIGURE 18.3 Residential demand tank-fed.

reduce consumption while maintaining a minimum level of supply is of the utmost
importance to optimize losses and conserve resources.
Some utilities are faced with the situation where they are not permitted to increase
their supply, due to environmental restrictions. Pressure reduction can be performed on
a zonal basis or indeed on an individual customer basis, as the situation requires.
Pressure reduction can also be used as an emergency measure for drought control;
levels of demand and leakage can be drastically cut until reserves return to normal.
Efficient Distribution of Water
Many water distribution systems have problems
supplying some customers, while others enjoy a
Pressure management is
constant source of water. The reason may be due to
aging infrastructure, poor design, geographic con- not only about pressure reduc-
straints, or demographic layout. Pressure manage- tion but also in some cases
ment using not only pressure reducing techniques, pressure increase, pressure
but also pressure sustaining techniques, boosters or sustaining, and surge control
flow control, can ensure that the system distributes and level management.
its resource as evenly as possible, ensuring required
volumes for a majority of the customers.
Guaranteed Storage
The implementation of pressure management schemes can assist the utility operators in
ensuring that reservoirs and storage tanks remain at realistic levels to meet demands.
This may be done using a mixture of pressure-reduction, pressure-sustaining, and flow-
control valves. See Fig. 18.4. Level control also ensures that storage is not allowed to
overflow during off peak hours when system demand and head loss is low and pres-
sures are at there highest. Reservoir overflows can form a large part of a utility leakage
if not properly controlled and calibrated.