In the face of global environmental challenges, it is increasingly important to introduce concepts of sustainability and responsible resource management from an early age. This paper presents an educational experience designed for nearly 80 students from 5th and 6th grade of primary education in Spain, aimed at raising awareness about the importance of wastewater treatment and its broader environmental implications. The activity was structured as a hands-on engineering workshop, adapted to the cognitive level of the students, where scientific content was integrated with civic and environmental values through an engaging and interactive format.

The main goal of the workshop was to foster a sense of responsibility in students regarding the proper use of water and the consequences of their actions at home. Emphasis was placed on distinguishing between appropriate and inappropriate behaviours when it comes to disposing of waste through domestic drains and toilets. By simulating scenarios and analysing real-life examples, students explored how individual actions can impact the larger urban water cycle, and how community-wide civic behaviour plays a crucial role in maintaining sustainable water systems.

Beyond raising awareness about the need for proper treatment of wastewater, the workshop introduced students to the “hidden potential” of wastewater treatment plants. These facilities do not only treatment water for reuse (regenerated water), but also allow for the recovery of energy, mainly through biogas produced by anaerobic digestion, and the extraction of organic matter that can be transformed into fertilizers. By understanding that wastewater is a resource rather than a waste, students were exposed to the principles of circular economy and the technological innovations that make water treatment a key enabler in environmental protection and climate action.

To assess the effectiveness of the workshop, students completed a brief knowledge test both before and after the session. This pre-post evaluation allowed us to measure the learning impact of the activity and provided clear evidence of knowledge acquisition and increased environmental awareness among participants. The results showed significant improvements in understanding the water treatment process, its environmental relevance, and the role each individual plays in the sustainability of water resources. By aligning with several Sustainable Development Goals (SDGs), particularly those related to clean water and sanitation, responsible consumption, and climate action, this initiative highlights the value of integrating environmental education into primary education.

Keywords: Circular Economy, Primary School Workshop, Sustainability Education, Wastewater Treatment, Civic and Environmental Responsibility.