The influence of a solvent on the substituent effect (SE) in 1,4-disubstituted derivatives of benzene (BEN), cyclohexa-1,3-diene (CHD), and bicyclo[2.2,2]octane (BCO) is studied by the use of polarizable continuum model method. In all X-R-Y systems for the functional group Y (NO2, COOH, OH, and NH2), the following substituents X have been chosen: NO2, CHO, H, OH, and NH2. The substituent effect is characterized by the charge of the substituent active region (cSAR(X)), substituent effect stabilization energy (SESE), and substituent constants sigma or F descriptors, the functional groups by cSAR(Y), whereas pi-electron delocalization of transmitting moieties (BEN and CHD) is characterized by a geometry based index, harmonic oscillator model of aromaticity. All computations were carried out by means of B3LYP/6-311++G(d,p) method. An application of quantum chemistry SE models (cSAR and SESE) allows to compare the SE in water solutions and in the gas phase. Results of performed analyses indicate an enhancement of the SE by water. The obtained Hammett-type relationships document different nature of interactions between Y and X in aromatic and olefinic systems (a coexistence of resonance and inductive effects) than in saturated ones (only the inductive effect). An increase of electric permittivity dearly enhances communications between X and Y for BEN and CHD systems.