Water losses: A global problem

The sustainable and integrated management of water resources is one of the most challenging global issues. Fresh water is a limited, sometimes even scarce, resource and rapid global changes such as population growth, economic development, migration and urbanisation are placing new strains on water resources and on the infrastructure that supplies drinking water to citizens, businesses, industries and institutions. Ensuring safe, sufficient and affordable water supply is becoming an ever more pressing issue for politicians and water professionals.

An aggravating factor in developing and transition countries, in particular, is the huge amount of water being lost through leaks in water distribution networks, referred to as physical or real water losses, and the volumes of water distributed without being invoiced, referred to as apparent water losses. The sum of real and apparent water losses and unbilled authorised consumption constitutes a water distribution network's non-revenue water (NRW). In 2006, the World Bank estimated that an average of 40 - 50% of the water produced in developing countries is non-revenue water (World Bank 2006). Developing countries are estimated to have an annual NRW volume of 27 billion m³ according to calculations drawn up by the World Bank based on an average of 35% of the system input water being lost. This represents approximately USD 6 billion in revenue that water utilities lose every year.

The role of water loss reduction

Water loss reduction (WLR) in general and pressure management in particular could play a significant role in improving this situation. For instance, halving the amount of lost water mentioned above would yield enough water to supply an additional 90 million people. Pressure management reduces real losses since decreasing pressure directly diminishes leakage from pipelines and household connections.

WLR often represents an efficient alternative to exploiting new resources, which frequently involves cost-intensive measures, such as new dams, deep wells, seawater desalination or even transferring water from one river basin to another. Therefore, water loss reduction and pressure management contribute to sustainable and integrated water resources management (IWRM).

Many strategies and methods for reducing water losses have been developed over the past two decades. Nevertheless, many water utilities around the world have yet to implement sustainable water loss reduction strategies despite their obvious benefits.

A sound WLR strategy consists of an initial situational analysis to assess and visualise non-revenue water in accordance with the water balance of the International Water Association (IWA) in which geographical-based information systems play a crucial role. In a second step, clear objectives and targets need to be formulated for the water distribution network. Finally, an action plan has to be devised for the implementation phase. The IWA Water Loss Task Force defined four principal methods for combating real water losses:

  • Pressure management
  • Active leak control
  • Speed and quality of repairs
  • Infrastructure management.

A single method or a combination of different methods will constitute the most efficient and economic instrument for WLR depending on the local situation.