Acesulfame is a sweetener in sugar-free drinks and foods. As it cannot be metabolized in the human body, the sweetener ends up in wastewater after consumption and remains largely intact even in sewage treatment plants. A new study shows that the persistence of the sweetener varies with temperature as the concentration of the sweetener in wastewater varies with the seasons. The environmental geosciences team analyzed how groundwater flows can be traced based on these seasonal fluctuations. Since residues of the sweetener end up in drinking water, acesulfame serves as an indicator of the origin and composition of our drinking water.Acesulfame is a sweetener in sugar-free drinks and foods. As it cannot be metabolized in the human body, the sweetener ends up in wastewater after consumption and remains largely intact even in sewage treatment plants. A new study shows that the persistence of the sweetener varies with temperature as the concentration of the sweetener in wastewater varies with the seasons. The environmental geosciences team analyzed how groundwater flows can be traced based on these seasonal fluctuations. Since residues of the sweetener end up in drinking water, acesulfame serves as an indicator of the origin and composition of our drinking water.