In the title water-solvated salt, C(21)H(22)P(+)·Br(-)·H(2)O, the ionic components are linked by short C-H⋯Br contacts along the a-axis direction. The two half occupied water mol-ecules are connected to each other by strong O-H⋯O hydrogen bonds and they are also linked to the bromide anion by short O-H⋯Br contacts.