In this study, samples were taken from the polymeric insulator parts of XLPE insulated medium voltage cables already used for energy transmission and distribution.These samples have been aged in a controlled manner in the laboratory environment. The applied voltage and frequency was adjusted 24 kVpp and 3 kHz respectively to initiate and grow water treeing in a short time period. The thickness of the samples taken from the polymeric insulator part of the cable was determined as 800 μm - 950 μm. The lengths, widths and geometry of water trees formed in saline solutions with different conductivities were analyzed. The study is mainly based on investigation the effect of external factors on the growth of water trees observed in XLPE type transmission and distribution cables.