New measurements of the amount-of-substance density of 11 mixtures of (water + carbon dioxide) are reported in the temperature range 415 K to 700 K at pressures from 6 MPa to 35 MPa. The results have been obtained using a fully-automated isochoric instrument. The average uncertainty of the density is estimated to be about +/-0.08 per cent for the mixture with the lowest water content, and +/-0.14 per cent for the mixture with the highest water content. Comparisons with independent sources of experimental data through a model based upon the two-fluid corresponding states principle are presented. The dew points of the mixtures studied have also been determined and are compared with values from the Peng-Robinson equation of state.