Sewage can serve as an indicator of public health in the Netherlands. Many diseases that occur within a group of people can be detected in sewage. This includes infectious diseases such as COVID-19 (caused by the coronavirus SARS-CoV-2) and non-infectious diseases. By examining sewage samples, we can also identify substances that tell us more about our lifestyle or living environment. Sewage research is useful and important, especially in conjunction with other forms of public health research.