  We construct a self-consistent model for the wind around W Hya by solving the
coupled equations describing the hydrodynamics and dust radiative transfer
problems. The model matches simultaneously the observed continuum radiation and
wind velocity profile. The water line emission is calculated next using the
water abundance as the only free parameter, fitted from the ISO observations of
Neufeld et al. (1996) and Barlow et al. (1996). The gas temperature is
determined from a thermal balance calculation that includes water as one of its
main components. Our model successfully fits all the observed water lines,
resolving a major discrepancy between the modeling results of the two observing
teams. The mass loss rate is 2.3 x 10^{-6} M_solar yr^{-1}, the water abundance
is 1.0 x 10^{-4} and the ortho:para ratio is 1:1.3.
