This research tracks the abnormal system operating conditions of the city of Asyut water supply
network over an extended period. EPANET software was used to perform hydraulic and water quality analysis.
Firstly, the effect of roughness variation with time on pressure head distribution and water quality through the
network is simulated. Secondly, leakage due to failure of some pipes on the flow, pressure heads and water
quality are investigated. Also the effect of closing some pipes in the network on pressure head and chlorine
distributions is taken into consideration. Finally, the effect of changing the source of chlorine disinfection on
water quality in the network is studied. The results indicate the following: (1) The increasing roughness of
pipes can significantly increase the head losses through the network and consequently decrease the head at
the end of network below the minimum limit. The variability in nodal pressures also has a significant effect
on chlorine decay if the bulk wall reaction coefficient is taken to be dependent on the roughness of the pipe.
(2) The failure of some pipes in the networks not only increases the consumed discharge in the network and
decreases the pressure head but also changes the flow directions in some pipes through the network. (3) Closing
a pipeline increases pressure in a region and decreases it at another and also changes the direction of flow in
the network. This may affect the chlorine distribution through the network. (4) Chlorine disinfection from one
source can significantly decrease the residual concentrations under the minimum limit in part of the network,
while it can increase variability in nodal concentrations.