Data Summary of The Fifth Unregulated Contaminant Monitoring Rule
This document provides available health-based reference values (i.e., reference concentrations and reference doses [RfDs]) and a summary of the analytical results to date for the contaminants being monitored under the fifth Unregulated Contaminant Monitoring Rule (UCMR 5). The health information and occurrence data will be updated approximately quarterly until completion of data reporting in 2026. Data are added and possibly removed or updated over the course of this reporting cycle following further review by analytical laboratories, PWSs, states, and the EPA.