This dataset contains the results of steady-state flow water permeability experiments conducted on samples of ballistically ejected blocks of dense plug rock from three active volcanoes: Soufrière Hills Volcano, Montserrat, West Indies and Reventador and Sangay volcanoes, Ecuador, South America. The dataset includes permeability measurements obtained under laboratory conditions at room temperature using varying effective pressures ranging from 5 to 40 MPa. Multiple cylindrical cores were prepared and tested from each field sample to assess permeability variability both within and between blocks. The data were collected, between April 2024 and January 2026, as part of the NERC-funded project NE/W008033/1 The explosivity of volcanic eruptions: Quantifying the critical role of permeability in magmas.