While it is unfortunate that some of the water models exhibiting the poorest agreement with experimental properties are some of the ones most commonly used with biological and materials force fields today, it does not necessarily invalidate such studies. In the case of the CHARMM force field, traditionally all other molecules are parameterized relative to the CHARMM TIP3P (TIPS3P in this study) water model and subsequently adjusted to reproduce other experimental data, which should ameliorate some of the deficiencies in that model. The CHARMM developers themselves have tested adjustments to the water model to improve agreement with experimental data. Moreover, as discussed by Onufriev and Izadi, water models that perfectly reproduce the bulk properties of water may in fact be poorer for some of the wide variety of hydrophobic and hydrophilic environments where water can be found, and the only solution is to carefully benchmark the system of interest to as much available experimental data as possible, regardless of the specific water model used. While the Class II force fields did not generally reproduce well the experimental properties examined in this study, these force fields are still potentially useful due to the variety of atom types available, transferrable nature of their parameters, and ability to reproduce other experimental phenomena. The PCFF force field, for example, was able to reproduce the triple helix stereocomplex of poly(methyl methacrylate) in agreement with experimental X-ray diffraction profiles. However, when used outside the commercial software they were parameterized for, Class II force fields should be used with caution, and may be better for comparison purposes between systems rather than for attempting to find absolute values. In the past decade, many studies have examined the feasibility of using some of the more recently developed water models with existing force fields. When done properly this can represent a significant advancement in the modeling of solvated systems, but it must be done with care. For example, it was found that when a force field that used arithmetic mixing rules for the Lennard-Jones interactions was mixed with ion parameters that were parameterized for geometric mixing rules, the salt spontaneously and unphysically crystalized from solution. Fortunately, new compatible ion parameters have been developed for the OPC, OPC3, TIP3P-FB, and TIP4P-FB water models. While the careful testing of newer water models with older force fields for biomaterials and other molecules is one solution, another current solution is to develop new force fields for compatibility with the more recently developed water models. Finally, while the accuracy limit may indeed have been reached for 3-point and 4-point non-polarizable models, other models for water are continually in development, such as the 7-point TIP7P, 161 the reactive force field ReaxFF, 162 the FFLUX polarizable and multipolar model, as well as others based on DFT and machine learning, to name a few. As computing power increases over the coming years, we expect that the ability to predict and reproduce the observed properties of water molecules will also continue to improve, which in turn will improve our understanding of this remarkable solvent.