Estimating physical unaccounted for water (UFW) in distribution networks using simulation models and GIS

Abstract

A methodology for evaluating leakage or physical ‘unaccounted for water’ (UFW) owing to high pressure in water networks is developed. Considering the crisis of water supply issues in large cities owing to increases in population, quantifying the UFW in terms of both physical and non-physical losses of water in the network to improve the system efficiency represents an important issue that managers need to consider. A pilot site is used to demonstrate the methodology, including the spectrum of network data for spatial and attributed data stored in a GIS database. Via use of an interface extension tool, the data were transformed into the EPANET model. After hydraulic simulation using mathematical formulae, leakage discharges from the network are quantified and the results provide estimates of the percentage of physical UFW, allowing comparison with the modelling and the measurements of total UFW in the network Physical losses in the pilot site area are determined to be 13% and the non-physical losses (e.g. under-registering of metered amounts) as 19.7%, for a total of 32.7% of the total water supplied.