Tetra­butyl­ammonium 4-hy­droxy­benzoate dihydrate

In the title compound, (n-C(4)H(9))(4)N(+)·C(7)H(5)O(3) (−)·2H(2)O, the carboxyl­ate group is twisted slightly out of the plane of the attached benzene ring, the two C—C—C—O torsion angles being −8.9 (2) and −10.7 (2)°. The anion inter­acts with two water mol­ecules through several O—H⋯O hydrogen bonds, forming wide ribbons along the a axis constructed from two anion–water chains. These ribbons are contained between unclosed diamond-like (16.2 × 15.0 Å) channels constructed by four rows of tetra­butyl­ammonium cations, which are arranged along the [011] and [01[Image: see text]] directions.