  We report on the fragmentation of the water molecule by $1$ MeV H$^{+}$,
He$^{+}$ and 650 keV N$^{+}$ ion impact. The fragment-ion energy spectra were
measured by an electrostatic spectrometer at different observation angles. The
obtained double-differential fragmentation cross sections for N$^{+}$ is found
to be more than an order of magnitude higher, than that for H$^{+}$. The
relative ratios of the fragmentation channels are also different for the three
projectiles. Additional fragmentation channels were observed in the spectra for
He$^{+}$ and for N$^{+}$ impact, which are missing in the case of H$^{+}$. From
the analysis of the kinetic energy of the fragments, the maximum observed
degree of ionization was found to be $q\rm{_{max}}=3$, $4$, and $5$ for
H${^+}$, He${^+}$ and N${^+}$ impact, respectively. Absolute multiple
ionization cross sections have been determined. They are compared with the
predictions of the classical trajectory Monte Carlo and
continuum-distorted-wave eikonal-initial-state theories. At lower degrees of
ionization, theories provide reasonable agreement with experiment. The
systematic overestimation of the cross section by the theories towards higher
degrees of ionization indicates the failure of the independent particle model.
