Public water supply in the modern sense of the word exists only 4.5 centuries. More precisely, it dates back to 1544, when the English Parliament passed a law on "clear water" supply for London citizens. In the mid-19th century, under the influence of the second industrial revolution, cities are rapidly evolving. The increase in the number of inhabitants and economic activities also increases the water demand. Water supply development is gaining momentum in Western Europe and North America. Until the beginning of the 20th century, most cities have sufficient access to the water with satisfying quality. This trend has continued to this day. With accelerated population growth, urbanization, environmental pollution, and already present effects of climate change, it is increasingly difficult to ensure and maintain sufficient quantities of drinking water. In the European Commission's reference document, water is a valuable natural resource to be managed in a sustainable manner, and all the losses of this resource should always be minimized. Water supply organizations face the challenge of establishing a balance between the efficiency of water supply networks and the efficiency of using natural, human, financial and other resources and are responsible for achieving the goals of a sustainable and efficient business. The problem of efficiency and sustainability of public water supply is a global problem, and water losses are generally considered an important issue. This particularly applies to the period after 1996 when an IWA4 (International Water Association) established a WLTF5 working group on water loss issues, with the task to standardize the water losses terminology and water balancing procedures, and introducing consistent indicators6 for assessing efficiency of the management and financial performances in water supply systems. Water losses in all water supply systems are caused by a series of operational and process reasons, and it is particularly worrying that in most water supply organizations the water losses grow over time, or in other words the efficiency of these organizations falls. Water supply systems are getting bigger, older and consequently more and more complicated for monitoring, management and maintenance. The consequence of such a situation is the continuous growth of negative business indicators. Water supply organizations in their efforts to improve their business use different approaches that are mostly reduced to repairing defects in the struggle with water losses. After few years of intensive efforts and seeking solutions for achieving better results or progress in the struggle with water losses, the expected results absent. The WLTF Working Group concludes that there is no significant shift in the efficiency of water supply organizations, and proposes a change in the behavior pattern and applying the latest knowledge and achievements to find an effective methodology for reducing water losses and the desired recovery of water supply systems. Water Loss Management will only be successful if it is introduced as part of the overall sustainable package of measures defined by the long-term strategy. At the same time, with a working group which tries to find solutions to increase the efficiency of public water supply, two new, mutually independent concepts have emerged in the global economic field, bringing significant improvements to the business of business entities. The concepts of Lean and Green Management and Industry 4.0 become the imperative of business success and an indispensable part of the production environment but also the leading manufacturing strategies in the world. By linking these three concepts into unique integral model WALEGRIN 4.0, a model which has been developed to improve efficiency of management for water supply system and its organization. By applying the principles of Lean and Green management and digitisation of business based on new ICT technologies, existing methods for water supply management have been improved. An integral model for effective public water supply management WALEGRIN 4.0 is an unique solution to the problem of increasing efficiency and can be applied to any public water supply organization.