For both water and heavy water adsorption and absorption on crystalline poly(vinylidene fluoride with trifluoroethylene (30%)), P(VDF-TrFE 70:30), two distinctly different adsorption sites have been identified by thermal desorption spectroscopy. One adsorbed water species resembles ice and there is also an absorbed water species that interacts more strongly with the polymer thin film, and in addition, there is a polymer surface (polymer to ice interface) water species. We find that there is H/D exchange between the water or heavy water molecules and the ferroelectric polymer (largely -(CH2-CF2)-), particularly at the polymer surface.