Heptaaqua­(3,4,5,6-tetra­chloro­phthalato-κO¹)erbium(III) 2-carb­oxy-3,4,5,6-tetra­chloro­benzoate–3,4,5,6-tetra­chloro­phthalic acid–water (1/1/1)

In the three-dimensional tetra­chloro­phthalate-bridged title complex [Er(C₈Cl₄O₄)(H₂O)₇](C₈HCl₄O₄)·C₈H₂Cl₄O₄·H₂O, the Er^III ion is coordinated in form of a distorted square antiprism by an O atom of a tetra­chloro­phthalate ligand and by seven water O atoms. Extensive hydrogen bonds establish a layered network structure extending parallel to (001).