The Water4All 2025 Joint Transnational Call invites research and innovation projects focusing on the connection between water and human health, with particular emphasis on water quality, contaminants, and sustainable water treatment technologies. The call follows the “One Health” approach, recognizing the interdependence of human, animal, and environmental health, and supports the development of efficient, cost-effective water monitoring and risk management methods. With a total budget of approximately €28 million, the call aims to contribute to evidence-based water policies at national, EU, and global levels; funded projects may run for up to 3 years.