Herein a review of substances detected in drinking water and groundwater found that 43 percent of them are registered under EU ⁠REACH⁠ Regulation (EC) No 1907/2006. In addition, a PMT/vPvM assessment was applied to all REACH registered substances (as of May 2017). Persistent, Mobile and Toxic (PMT) and very Persistent, very Mobile (vPvM) substances pose an intrinsic hazard to the sources of our drinking water. Data quality considerations are included, along with a preliminary emission assessment and cost/benefit considerations. Of the complete list of PMT/vPvM substances, 122 chemical constituents are prioritized for further investigation to assess the need for introducing risk management measures.