Bis[μ-2-(4-hy­droxy­phen­yl)acetato]-κ(3) O,O′:O;κ(3) O:O,O′-bis­{aqua­(4,4′-bi­pyridine-κN)[2-(4-hy­droxy­phen­yl)acetato-κ(2) O,O′]erbium(III)} monohydrate

The title dinuclear complex, [Er(2)(C(8)H(7)O(3))(6)(C(10)H(8)N(2))(2)(H(2)O)(2)]·H(2)O, contains two Er(III) atoms in the asymmetric unit, six 2-(4-hy­droxy­phen­yl)acetate (PAA) anions, two 4,4′-bipyridine (bipy) mol­ecules, two coordinated water mol­ecules and one solvent water mol­ecule. The central Er(III) atoms are nine-coordinated. The coordination environment includes six O atoms from three PAA anions, one bridging O atom from a PAA anion, one O atom from a water mol­ecule and an N atom from a bipy ligand in a distorted tricapped trigonal–prismatic geometry. The occurrence of numerous O—H⋯O and O—H⋯N hydrogen bonds involving coordinated and noncoordinated water as well as bipy groups builds up an intricate three-dimensional network.