Polymer materials thatare used in outdoor enviroments are exposed to humidity and polution. Inaddition, some insulation materials installed in water or embeded to slushcontaining serious pollutants for a long time. These conditions adverselyaffect the dielectric properties of insulating materials. In this study, theprepared unsaturated polyester (UPE) samples are stored in an ionized watersolution for 8, 24, and 168 hours. This ionized water solution is considered torepresent the polluted water in the outdoor environments. Further, thedielectric behaviors of the prepared polyester samples are investigated usingthe inclined plane test (IPT) method, whereas the leakage current data that arerecorded during the experiment are analyzed using the recurrence plot (RP)method. The results of applying the inclined plane test on the unsaturatedpolyester samples depict that the lifetime of the samples decreased with anincrease in the period of storage in the ionized water solution. Further, theresults of the recurrence plot analysis reveal that the recurrence plot pointdensity also depicted a decrease with an increase in the period of storage inthe ionized water solution.