Protecting the sources of our drinking water from any threats caused by chemicals is of the utmost importance. A strategy is needed in order to allow Europe’s chemical industry to continue to innovate while ensuring the protection of the water cycle. The German Environment Agency (UBA) is carrying out an initiative to identify those substances that are persistent (P) in the environment, mobile (M) in the water cycle (PM substances), and additionally toxicity (T) to human health (PMT substances). The proposed criteria will assist registrants in fulfilling their responsibility of guaranteeing the safe use of chemicals under the EU’s chemical regulation “REACH” (Regulation EC No 1907/2006).