The European Commission is aiming to taking action at the UN Global Harmonization System level to include the new European PMT/vPvM hazard classes (Persistent, Mobile and Toxic / very Persistent and very Mobile) to proactively identify those chemicals that have an intrinsic propensity to readily reach potential sources of drinking water. This proposal builds on the so-called PM concept according to which Persistence (criteria of EU-REACH Annex XIII) and Mobility (log Koc < 3) would be proxies for a substance’s degradation potential and transport velocity, two processes believed to drive the potential for contamination. Two studies (Arp et al., 2017; Schulze et al., 2018) identified hundreds of substances with assumed PM properties via QSARs. Researchers selected some of these substances for monitoring in surface and groundwater and concluded that the PM concept was fit for purpose (Montes et al., 2019; Schulze et al., 2019, 2020). However, independently, ECETOC (2021) reached an opposite conclusion based on a different dataset. In the present work, the Persistence of the aforementioned substances was reassessed based on all experimental data available. A substantial portion of the substances (20-35%) were erroneously concluded as P by the researchers. Our reinterpretation of the data indicates that PM properties do not increase the likelihood of detection in surface or groundwater and do not have any influence on contamination levels. Besides, 20-60% of the assumed PM substances were not detected in any water despite being selected for their assumed environmental release. Therefore, there is no evidence that PM properties are drivers of surface or groundwater contamination. Inclusion of PMT/vPvM into classification frameworks is unlikely to appropriately identify substances of concern for drinking water sources. Chemical presence in surface and groundwater is likely driven by a more complex combination of e-fate and emission factors.