Monitoring Nonrevenue Water Performance in Intermittent Supply

Taha Al-Washali,Maria Kennedy,Fadhl Al-Nozaily,Saroj Sharma,Mansour Haidera

doi:10.3390/w11061220

Taha Al-Washali, Maria Kennedy + Show 3 more

Open Access

https://doi.org/10.3390/w11061220

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Abstract

Water utilities should monitor their nonrevenue water (NRW) levels properly to manage water losses and sustain water services. However, monitoring NRW is problematic in an intermittent water supply regime. This is because more supplied water to users imposes higher volumes of NRW, and supplying significantly less water results in an unmet water demand but interestingly less NRW. This study investigates the influence of the amount of water supplied to a distribution system on the reported level of NRW. The volume and indicators of NRW all vary with variations in the system input volume (SIV). This is even more critical for monitoring NRW for systems shifting from intermittent to continuous supply. To enable meaningful monitoring, the NRW volume should be normalised. Addressing that, this research proposes two normalisation approaches: regression analysis and average supply time adjustment. Analysis of the NRW performance indicators showed that regression analysis enables the monitoring of NRW and tracking its progression in an individual system only, but not for a comparison with other systems. For comparing (or benchmarking) a water system to other systems with different supply patterns, the average supply time adjustment should be used. However, this approach presents significant uncertainties when the average supply time is less than eight hours per day.

Highlights

Supplying water to the residents of a city while minimising water losses in distribution systems is a challenge faced by water utilities worldwide
The supply network is geographically divided into six administrative zones, and each zone is subdivided into distribution areas, in which a total of 369 areas are interlinked and multifed
Monitoring nonrevenue water (NRW) and performance indicators (PIs) in an intermittent water supply regime is significantly influenced by system input volume (SIV)

Summary

Introduction

Supplying water to the residents of a city while minimising water losses in distribution systems is a challenge faced by water utilities worldwide. Nonrevenue water (NRW) is the difference between the amount of water added to a distribution system and the amount sold to the customers [1]. The estimated global volume of NRW is 126 billion cubic metres per year, costing approximately US $39 billion annually [2]. NRW either originates from leakages that occur at mains, storage reservoirs and customer connections, or commercial losses that occur due to customer meter under-registration, errors in data handling and billing or unauthorised use. The impact of NRW is substantial [3,4], as it accounts for considerable water wastage, affects the technical stability of the water supply, deteriorates the quality of water and water services, increases the operating costs and reduces revenues that should sustain and expand access to water. Assessing NRW involves quantifying water losses in a particular system without considering their actual locations [5,6]

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