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A water distribution network is the most expensive component of a water supply system; consequently the overall planning, installation , and rehabilitation processes should be implemented accurately and carefully. The main issue that developing countries are facing is how to optimize the distribution network to meet increasing water demand. To tackle the issue, this paper proposes a new concept for rehabilitation and expansion of a water distribution network while ensuring cost-effectiveness and adequate water pressure. The main framework of the pipe network is formulated based on the concept of a ″Trunk/limb Mains Reinforced pipe system″ (TMR system). Reinforcement of trunk/limb mains in the network is carried out selectively, requiring proper selection of pipelines and of trunk/limb pipe diameters. A multi-step genetic algorithm was developed to obtain the objective of selecting an optimal solution design for pipeline selection and trunk/limb mains diameters. To clarify the effectiveness of this concept, cost analysis was performed. The result indicates that application of this method offers advantages for rehabilitation and expansion, in that not only meeting increasing water demand but also cost-effectiveness and desirable hydraulic conditions can be achieved in the network.

Discharge, head, flow velocity and Reynolds number are flow parameters in pipe networks. On the other hand, energy loss is one of the factors that affect the capacity of the pipe as a means of distributing water flow. Energy loss is caused by several factors including the roughness of the pipe walls associated with the pipe material. Due to the lack of attention to the interrelationship of these factors, sometimes there are piping networks that do not work optimally or do not function as expected. The purpose of this study was to determine the effect of changes in discharge and head on flow parameters and energy loss in the piping network. This study uses experimental research conducted in the laboratory. The primary data collection is quantitative analysis with the main data collection through measurements using a series of pipes as a test model, and is preceded by the collection of supporting data, namely the analysis of the characteristics of the water sample. The characteristics of the water samples used are density (ρ) 1,000 kg/m3, kinematic viscosity 0.804 x 10-6 m2s, dynamic viscosity (μ) 0.801 x 10-3 Nd/m2, viscosity 8.5x10-7 m2/sec, and specific gravity (y) 1.00355 gr/cm3, and a temperature of 29.50C. There are 3 discharge variations used, namely Q1 = 0.004 m3/s, Q2 = 0.003m3/s and Q3 = 0.002 m3/s and variations in head H1 = 2 meters, H2 = 1 meter and H3 = 0.5 meters. The results showed that due to changes in discharge and fall height caused an effect on flow parameters in the piping network. The greater the discharge, the greater the energy loss, and the greater the head, the smaller the energy loss. Changes in flow rate have a more significant effect on changes in energy loss when compared to changes in head.

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