Characterisation of pressure and physical water losses in water distribution ystems using Epanet The Case of Southern Region Water Board, Thyolo Boma

Abstract

The study evaluates and characterises pressure in the existing Water Distribution System at Thyolo Boma. It investigates major factors causing pipe failures leading to high physical water losses with overall Non-Revenue Water of as much as 44%. The main objective was to reduce physical water losses through application of pressure management using EPANET models. Much focus was on the analysis of hydraulic regimes particularly dynamic operating pressure, unit head loss and velocity. A loss factor of 1.44, representing the system’s UFW was applied on billed water consumption to determine base demand at nodes as EPANET input data. GPS was used to determine ground elevations. An analysis of faults register was carried out to determine rates of pipe bursts per kilometre per year (bursts/km/year) that is compared with pipe characteristics and EPANET results to establish correlations from which conclusions were drawn. Results show that 42 percent of the distribution pipeline is in very high pressure zone while the rest is in low to moderately high pressure zones. Pipe bursts occur in high pressure zones with the exception of a few areas where pipe bursts emanate from poor pipe installation practices. High pressures are as a result of wide variations in topography. Application of some pressure management strategies like replacement of deteriorated pipes on a section of one of the high pressure zones proved effective in eliminating pipe bursts that consequently reduced leakage and hence reduction of physical water losses. In summary, leakage is primarily driven by differences in pressure in the distribution system. Introduction of pressure-break and pressure regulating facilities brought pressures to within permissible levels which will reduce pipe bursts, leakage and consequently physical water losses. Any effort to reduce excess pressure will reduce pipe failures that ultimately reduce physical water losses and thus improve operational efficiency.