Background Water is probably the world’s most precious and scarce natural resource. However, water networks in Italy typically lose around half of their supply through leakages. Furthermore, the processing and treatment of water is one of the largest environmental polluters. The most sustainable approach to improving water management is to make more efficient use of water resources, principally by reducing leakages. This will increase the effective supply to households and businesses, and prevent the exploitation of new water resources. Reducing leaks also reduces pumping costs – and the associated impact on the environment – for the same amount of water. An efficiently operated network provides an adequate quality of service to customers at the lowest operational cost. Such a network strikes the right balance between the costs and benefits of actions to lower leakage levels. Objectives The objective of the PALM project was to develop a Decision Support System to allow water companies to identify the optimum balance between reducing water leaks and being economically sustainable. Ultimately, the aim was to enable water companies to reduce water loss by around 50% and the related environmental impacts by up to 60%. The Decision Support System would integrate existing state-of-the-art technology to form what should be the most advanced water-efficiency system. It would use the latest acoustic instruments to locate leaks for repair. Other leakage control measures included applying a calibrated hydraulic model for the optimum configuration of the water system. The project identified valves to be closed and defined the optimum size of the flow meters and pressure-reducing valves. Pumping costs and the potential benefit of optimising the use of the pumps, exploiting low tariff periods and making better use of the available storage capacity would be examined, combined with an assessment of the costs of leakage detection and repair. This information would allow a typical cost-recovery ratio to be calculated. The project would thus provide water companies with the information they need to implement leakage repairs in the most efficient and effective way, and without compromising their economic sustainability. Results Considering high leakage in the distribution networks to be one of the main causes of reduced availability of potable water resources, the PALM project developed a Decision Support System to allow water companies to identify the optimum balance between reducing water leaks and being economically sustainable. The project has broadly achieved its aims, and even exceeded them in terms of accuracy and applicability. Furthermore, it has paved the way for further developments in this area. The main project tool, the DSS - Efficiency Calculator, was demonstrated and validated on the network of Perugia (a representative medium-sized EU town of 500 000 km2 with a population of 170 000). The tool was designed to define the optimum leakage value for any network, simply by inputting the key characteristics of the network itself. The production and intervention curves are defined in order to determine the optimum economic production level and hence the allowable losses. It is therefore applicable to most water networks given that it was designed to take account of the many variables of water systems. The software is relatively user friendly and quick to apply. Even the most complicated networks can be analysed within a few hours. The data to be inserted have deliberately been kept to a minimum and are related to what is normally readily available to a water utility. In fact, the major limiting factor is the burden of data collection. During the applications of PALM to other networks outside of Perugia, the data collection proved the most time-consuming activity, not because data was not available, but because it was in an easily extractable format. Often pump and reservoir data are held by the production department, consumption data by the billing department, economic data by the administration department and network data by the distribution department. PALM is unique in that it offers a realistic network-specific solution to the question: how low should leakage go? The relevance of PALM for the EU legislative framework is potentially huge as it is a tool that both regulators and utilities can use to set realistic targets on a system-by-system basis. The potential for replication is also great: the system can be replicated with immediate and significant benefits wherever water losses in the network pose a threat to the distribution of potable water resources. This especially applies to southern EU countries. The project partners consider the project tool to be the most appropriate one currently available for defining the target level of leakage, as it is based on economic considerations and takes into account the specific characteristic of any network. This is demonstrated by the considerable interest that it has generated among stakeholders. It surpasses the current approach that usually involves a fixed target (commonly a percentage), which is inappropriate as it does not take into consideration the quantity of water lost or, more importantly, the economic consequence of that loss both in terms of investment to recover it and the burden on the tariff that the customer has to pay. In light of the project results, water legislation and policy could be amended to facilitate initiatives such as the ones implemented by the project. PALM could be incorporated into defining the regulatory policy and the setting of realistic targets. There is the need to improve efficiency for the benefit of the customer and the environment as a whole. This means that in any given network, the investment should be tailored to maximise the returns. In this way the tariff will be minimised. PALM is capable of finding this point for any given network. Given that the Blueprint to Safeguard Europe's Water Resources (2012) outlines actions that concentrate on better implementation of current water legislation, integration of water policy objectives into other policies, the results of the project are certainly a step in this direction. Sustainability in the long term resides in the ability of the project tool to counter environmental and economic concerns. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan(see "Read more" section).