NRW System Analysis and Modelling

Before any WDM intervention is implemented, it is normal practice to undertake an investigation of the area in question in order to assess the key problems and to propose a strategy to address them.

Considerable progress has been made in modelling customer‐side demand management programs. Detailed models also exist to evaluate the costs and benefits of non‐revenue water reductions.  

The paper suggests a simple methodology for initial Non-Revenue Water (NRW) assessment which can be applied prior to a detailed water audit. The performance indicator suggested is NRW expressed in litres per service connection per day.

The Western Highveld area is located some 100 km north east of Pretoria and supports a population of approximately 650 000, most of whom live in peri-urban areas.

The 2nd Edition of the IWA Manual of Best Practice, ‘Performance Indicators for Water Supply Systems’ (Alegre et al, 2006) updates the 1st Edition (Alegre et al, 2000).

The development of quick and practical methods for calculating economic leakage levels is a stated objective of the Water Losses Task Force.

The solution to reducing and sustaining water distribution system leakage to economic levels is different in utilities around the world, however the need to be able to reduce leakage and identify the correct levels of operating and maintenance budget versus capital investment budget to apply to any particular problem over short, medium and long term time horizons can be complex.

In Germany, leakage management was never as much of an issue as in England. The infrastructure is in relatively good condition, preventive maintenance is done excessively, and billions of Deutschmark were spent since World War II to renew, rehabilitate and extend the distribution networks.

One of the major challenges facing water utilities around the world but especially in Low and Middle Income Countries (LAMIC) is the high level of water losses either through physical losses (leakage) or commercial losses (customer meter underregistration and theft of water in various forms).

Within the last few years there has been a growing realisation that the rapidly increasing water demands throughout South Africa are not sustainable and that if the growth in demand is not curbed, the country will face a serious water crisis early in the next century.

The paper describes the application of the IWA WLTF Approach in Italy with particular reference to implementation of IWA Water Balance and Performance Indicators to case studies, training courses for Water Utilities staff and National User Group activities

Khayelitsha is one of the largest townships in South Africa and is located approximately 20 km from Cape Town on the Cape Flats (a large flat sandy area at or near sea level).

The global volume of Non-Revenue Water (NRW) has recently been conservatively estimated at 50 billion cubic meters/year, and valued at US$15 billion. These figures highlight the problems that many water utilities experience in attempting to reduce NRW.

The IWA methodology of determining and comparing leakage in water distribution systems is now generally accepted as world‟s best practice in many countries around the globe.

An accurate water balance (water audit) is the foundation on which a water loss reduction strategy is founded. It is significantly more difficult to determine an accurate water balance if a large proportion of legitimate consumption is not metered.

Understanding and managing leakage in potable water distribution systems has always posed interesting and often difficult problems to the water supply authority.

Development of quick and practical methods for calculating economic leakage levels in international situations has been a stated objective of the IWA Water Losses Task Force since 2001.

Since the level of water losses from potable water distribution systems is one of the key efficiency issues, it would be expected that reliable performance indicators are used for benchmarking, international performance comparison or target setting.

The annual volume of water lost is an important indicator of water distribution efficiency, both in individual years, and as a trend over a period of years. High and increasing water losses are an indicator of ineffective planning and construction, and of low operational maintenance activities.

This report on The Issues and Challenges of Reducing Non-Revenue Water benefited from discussions with and review by members of ADB’s Water Committee, in particular the Urban Water Stream. Special thanks go to Joanna Masic in ADB’s East Asia Department for her detailed comments.