Background Tunisia has a semi-arid climate, characterised by high variations in rainfall over time and in different places. The protection of water resources is a national priority in Tunisia and areas where rainfall accumulates are of particular strategic importance. Protecting these areas from all forms of pollution and contamination is essential to ensuring the quality of the water supply. However, at the launch of the project, water quality in Tunisia was degrading due to diffuse pollution from the agricultural use of pesticides and fertilisers, discharges of untreated urban and industrial wastewater in lakes, rivers, and wadis, and contamination from solid waste dumped near water. This pollution of water resources represented a significant risk to public health. Tunisia already had a legal framework for controlling water pollution. However, its application and enforcement was still weak. This was mainly because of a lack of monitoring and institutional capacity in the Tunisian authorities and unenforceable standards. There was no assessment of the pollution sources and no framework for the coordination and exchange of information amongst the relevant authorities. Objectives The principal objective of the COPEAU project was to reinforce the capacity of the National Environmental Protection Agency of Tunisia (ANPE) in its work of controlling water pollution. It sought to improve institutional and technical capacity to intensify sampling and analysis of water resources and data treatment. It thus sought to make a positive impact on improving the quality of Tunisia’s water resources. The project aimed to provide technical expertise to the ANPE to improve its ability to protect water resources. Planned activities included the development of a manual of procedures and the training of staff. It also sought to promote coordination between stakeholders in charge of water monitoring, and upgrade the local monitoring equipment. The project hoped to pave the way for implementing the ‘polluter pays’ principle through improved monitoring and law enforcement by the responsible authorities. An additional objective of the project was to act as a model for other countries in the region with the aims of improving water supplies and reducing health risks. Results The COPEAU project succeeded in increasing the capacity of the ANPE to protect water quality in Tunisia. It established a common framework for all water protection actors to monitor water quality, also increasing the monitoring capacity even in remote areas and providing a reference for water quality protection in the wider region. The Belgian partner Aquapole provided the necessary technical expertise throughout the project. Aquapole is a science and research centre specialising in water science located within Liege University. It provided seven technical training sessions for ANPE staff, in both Tunisia and Belgium. It also elaborated a comprehensive manual of sampling and analysis procedures, including the treatment and evaluation of the information thus obtained. With the support of the LIFE programme and the Tunisian government, the project team acquired three mobile laboratories, which considerably enhanced the capacity of the ANPE to conduct systematic surface and groundwater analysis also in more remote areas of Tunisia. The project helped provide a common framework and reference procedures within which the different legal and technical water protection agents could work more coherently and successfully together. During the 3.5 years of project, the number of analyses carried out by ANPE was quadrupled and was expected to double once again until the end of 2010. Whilst initially ANPE only assessed seven water basins, by the end of the project it had the capacity to survey 138 basins. ANPE published the results of its water analyses in regular information bulletins and in greater detail within its annual report. The COPEAU project made an important contribution to broader efforts to improve management of Tunisian water resources. It fit alongside other Tunisian projects PISEAU II and SINEAU, which worked to improve water infrastructure and information systems respectively. These efforts should enable the Tunisian authorities to effectively monitor water quality and bring those responsible for pollution to justice. They should also provide a good example for the North African region. The beneficiary already agreed a new form of co-operation with the Algerian authorities on a shared approach to better control and manage common water basins.