Pipes burst and leakage rates in water distribution networks are growing with increasing of pipes age. Therefore, pipe rehabilitation and replacement programs would be necessary during the pipes life time. This is a complicated problem in which budget restriction has an important impact. This paper introduces a simple model to determine the best time for leak detection and pipe replacement programs using pipes break records. Assuming a linear relationship between pipes break rate with time, the operation cost for three different steps of: pipe repair, leak detection and pipe replacement are evaluated and the best time for commencing of each scenario is calculated. To highlight advantages of the proposed methodology, it is applied to a pipe network in one of the Iranian cities. At first pipes break records are gathered for a period of six months using a standard format. Then the best time for leak detection and replacement programs are determined and sensitivity of the results to different parameters is evaluated. It can be concluded that the proposed methodology produces a powerful tool to be used in water distribution networks and help decision makers to choose the best option considering budget restrictions.
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