The title compound, C7H8NO3+.Cl-.H2O, crystallized in the centrosymmetric space group P21/c in an ionic form, the proton from HCl having been transferred to the amino N atom. The three H atoms on N, the H atom on the carboxyl group, the H atom of the hydroxyl group and the H atoms of the water molecule, all of which are involved in hydrogen bonding, are ordered. The eight `best' hydrogen bonds have the following donor-acceptor distances: OO 2.681 (2) and 2.598 (2); OCl 3.367 (1), 3.345 (2) and 3.156 (2); NO 2.995 (2); NCl 3.173 (2) and 3.114 (2) Å. In this structure, the acid cations are not linked directly to each other by hydrogen bonds, but are linked indirectly, via hydrogen bonds involving chloride ions and water molecules, into a three-dimensional network. Through basic second-level graphs, finite patterns substantially outnumber chains and rings.