Abstract
In the structure of the title compound, C13H14N2O3 center dot H2O, all atoms of the organic molecule except the terminal methyl group of the ethyl group attached to the N atom of the pyridinone ring are roughly coplanar, with an r.m.s. deviation of 0.0897 angstrom. In the crystal, C-H center dot center dot center dot O contacts link pairs of naphthyridine molecules into head-to-tail dimers. These are joined by strong O-H center dot center dot center dot O hydrogen bonds from the water molecules into infinite chains along the a axis.