Thomas ter Laak is a researcher in Chemical Water Quality. Both as a theme coordinator of the theme group Nieuwe Stoffen [New Substances] and in terms of content, he works on the sources, behaviour and prevention of (new) substances in drinking water (springs). Over the past years, Thomas did research into the sources and prevention of medications and their transformation products in the watercycle and modelling their emissions, loads and concentrations in surface waters. He also does research with colleagues on all kinds of unknown substances in drinking water springs and attempts to gather more information on the identity of these unknown substances through so-called ‘suspect screening’. Thomas does work at Wageningen University, where he supervises a PhD student doing research on dynamics and modelling of emissions of micropollutants resulting from wastewater purifications and possibilities for ‘soil retention filters’ to limit emissions. Furthermore, Thomas is a teacher for the course ‘Drinking water and sanitation’ of the ‘Water Science and Management’ course programme at Utrecht University.