It is one of the most pressing environmental problems of our time and yet largely unknown: The pollution of our waters by nitrogen. EOOS has developed the revolutionary prototype of a toilet for urine separation (urine trap), which offers a systemic design solution to fight the global nitrogen problem. The official Austrian contribution to the XXII International Exhibition of La Triennale di Milano 2019 presents the urine trap embedded in a multimedia installation that illustrates the ecological interaction of coastal waters, sewage systems and agriculture.