This baseline report details the premises of PWN in Andijk, where the LIFE WATERSOURCE project is set to be constructed. The report outlines the current challenges faced by PWN, which supplies drinking water to nearly 2 million people in North-Holland, primarily using water from Lake IJsselmeer. It describes the intensive treatment process that involves significant energy and chemical use, alongside issues stemming from climate change, such as increased water temperatures and saltwater intrusion. To address these challenges, PWN is implementing nature-based solutions to enhance water purification and sustainability. The report also discusses the construction of a 'Climate buffer' aimed at improving freshwater availability and ecological quality through the creation of wetlands and a natural purifying ecotope. The findings from various preparatory studies, including hydrological and ecological assessments, indicate that the site is suitable for the demonstration of these nature-based pre-treatment steps, ensuring minimal impact on the surrounding nature.