In the reaction field theory of solvation, penetration of charge density outside the cavity nominally enclosing the solute leads to a volume polarization that contributes in addition to the commonly recognized surface polarization. In principle the exact volume polarization charge density is spread everywhere outside the cavity, but its effect can be closely and concisely simulated by a certain additional surface polarization charge density. Formal comparison is made to conductorlike screening models, and it is found that these improve on common approaches that neglect volume polarization by automatically including the simulation of volume polarization. A revised method to numerically determine this simulation is also described.