The elasticity of single-crystal hydrous pyrope with similar to 900 ppmw H2O has been derived from sound velocity and density measurements using in situ Brillouin light spectroscopy (BLS) and synchrotron X-ray diffraction (XRD) in the diamond-anvil cell (DAC) up to 18.6 GPa at room temperature and up to 700 K at ambient pressure. These experimental results are used to evaluate the effect of hydration on the single-crystal elasticity of pyrope at high pressure and high temperature (P-T) conditions to better understand its velocity profiles and anisotropies in the upper mantle. Analysis of the results shows that all of the elastic moduli increase almost linearly with increasing pressure at room temperature, and decrease linearly with increasing temperature at ambient pressure. At ambient conditions, the aggregate adiabatic bulk and shear moduli (K-S0, G(0)) are 168.6(4) and 92.0(3) GPa, respectively. Compared to anhydrous pyrope, the presence of similar to 900 ppmw H2O in pyrope does not significantly affect its K-S0 and G(0) within their uncertainties. Using the third-order Eulerian finite-strain equation to model the elasticity data, the pressure derivatives of the bulk [(partial derivative K-S/partial derivative P)(T)] and shear moduli [(partial derivative G/partial derivative P)(T)] at 300 K are derived as 4.6(1) and 1.3(1), respectively. Compared to previous BLS results of anhydrous pyrope, an addition of similar to 900 ppmw H2O in pyrope slightly increases the (partial derivative K-S/partial derivative P)(T), but has a negligible effect on the (partial derivative G/partial derivative P)(T) within their uncertainties. The temperature derivatives of the bulk and shear moduli at ambient pressure are (partial derivative K-S/partial derivative T)(P) = -0.015(1) GPa/K and (partial derivative G/partial derivative T)(P) = -0.008(1) GPa/K, which are similar to those of anhydrous pyrope in previous BLS studies within their uncertainties. Meanwhile, our results also indicate that hydrous pyrope remains almost elastically isotropic at relevant high P-T conditions, and may have no significant contribution to seismic anisotropy in the upper mantle. In addition, we evaluated the seismic velocities (nu(P) and nu(S)) and the nu(P) /nu(S) ratio of hydrous pyrope along the upper mantle geotherm and a cold subducted slabs geotherm. It displays that hydrogen also has no significant effect on the seismic velocities and the nu(P) /nu(S) ratio of pyrope at the upper mantle conditions.