Who we are
The IWA Water Loss Specialist Group (WLSG) is one of the International Water Association’s most active specialist groups. We have organised the biennial Water Loss Conference since 2002 and grew out of the IWA Water Loss Task Force first convened in the 1990s. We bring together practitioners, researchers, utilities and regulators to share knowledge and drive measurable improvements in water loss management worldwide from more than 70 countries.
We are a fully volunteer-led network. Everyone who contributes does so out of genuine commitment to sustainable water management. Membership is open to all IWA members, at no extra cost, and our guidance and publications are free for anyone to download.
Our Mission
The objective of the WLSG is to research and advance knowledge in water loss reduction for the benefit of water industry governance bodies, utilities, practitioners, associated individuals and companies, community representatives, and government bodies at all levels, including national and international agencies.
The WLSG seeks to assist in the reduction of water losses globally and contribute to reducing future water demand, through engaging in advocacy, capacity building, technology transfer, and the development of standardised frameworks and benchmarks in an impartial way.
Given that a significant portion of the WLSG’s work relates to challenges in Low and Middle-Income Countries (LMICs), the group shall ensure meaningful representation of, and engagement with, these regions in its governance, working plan, and activities.
Our History
In 1995, the IWA Operations and Maintenance Committee, chaired by Dr Wolfram Hirner, established the first Water Loss Task Force. It had objectives of recommending standard international terminology for calculating real and apparent losses and reviewing performance indicators suitable for international comparisons.
The first group consisted of Allan Lambert, Timothy G. Brown, Masanori Takizawa and Dieter Weimer. Its findings were published in the late 1990s and incorporated into the first edition of the IWA publication on performance indicators for water supply services.
Period between 1997 and 2000 effectively created the theoretical core of NRW as a discipline: a standardized water balance, a controlled vocabulary, and the first internationally comparable performance indicator for real losses (ILI), designed to replace the crude and misleading “% of system input volume” metric. Allan Lambert, Roland Liemberger, Albert Alegre, Renato Hirner and others have built the foundation of the NRW theory as we know it now.
After the 2001 IWA conference in Brno, specialists who had begun using the Water Balance and ILI formed a second task force. The work continued under professionals including Ken Brothers, Bambos Charalambous, Stuart Hamilton and Tim Waldron. In 2010, the task force became the IWA Water Loss Specialist Group.
From roughly 2011 onward, NRW management moved from a specialist technical niche into mainstream utility governance and development-finance policy, accompanied by World Bank and Asian Development Bank publishing policy and operational documents treating NRW not merely as a technical/hydraulic problem but as an institutional, financial, and governance one, including first Performance-Based Contract Guidance to manage NRW contracts.
From around 2024 WLSG became one of the IWA’s largest and most active specialist groups, running the biennial International WaterLoss Conferences with more than 800 attendees and supporting Regional Water Loss events.
From 2026 onward marks a distinct step-change for the group towards formalisation and global expansion, driven by both external growing interest and recognised importance of water loss in the world, and internal expantion of the group and its activities. The group extended its between-conference presence with a regular newsletter and dedicated YouTube channel, broadening free access beyond conference attendees.