Abstract: Leakage in pipeline networks leads to excessive economical losses as well as poses environmental hazards. The leakage detection has been addressed by many researchers throughout the last few decades by using various techniques. Nowadays, these techniques have been modified and enhance to be faster with the advanced technology in sensors and computers, so this area of research has to be revisited. In the present study, the occurrence of leakage in a single branched pipeline system has been investigated theoretically and verified experimentally. The theoretical model of a proposed pipeline system has been modeled by applying the governing fluid flow equations using MATLAB capabilities. The pipeline system in the investigation has been supplied with water from a constant head tank. The pipeline system used in the theoretical investigation, of leakage detection, has been realized (established) practically in the Fluid Mechanics Laboratory of the Mechanical Power Department in the Military Technical College. The fluid flow parameters such as: pressure in the pipeline, volume flowrate, leak location, and leak flowrate have been measured in both conditions of pipeline flow; without and with leakage occurrence. To investigate the effect of leakage occurrence on the pipeline parameters (pressure and flowrate) at pipeline entrance section, both the leak locations and the leak opening diameters have been varied in the theoretical model and experimentally. The ranges of leak location, x/L, is from 0.05 to 0.95 and the ranges of leak diameter, d/D, is from 0.2 to 0.7. The results of the theoretical investigation and the experimental measurements have been in good agreement. It has been found that, the fluid flow parameters, pressure and flowrate, at entrance of the pipeline system are greatly affected by the leak location and its opening size. So the detection of leak location and its flowrate could be predicted, from the information of changes in the pipeline pressure and flowrate at the entrance of the pipeline system after leakage occurrence.