The aim of this research is to study the effects of different concentrations of water on both incoming and outgoing in central biological and chemical wastewater treatment plant in Manisa (Turkey) organized industrial zone (MOIZ) on the Allium cepa L. root meristems, having been rooted in distilled water for 48 h. The union bulbs were kept in the 100% concentrations of the refined water (RW) and of 10, 25, 50 and 100% concentrations of unrefined water (UW). Distilled water was used for the control samples. It was determined that wastewater reduced the rate of the mitotic division of different concentrations and increased the mitotic anomalies. Mitotic index was found to be 33.8, 31.2, 23.6 and 16.7% in the control group, RW, 10% concentration of the UW, and 25% concentration of the UW, respectively. On the other hand, the rates of Mitosis / (Anaphase + Telophase) were 0.23, 0.28, 0.42, 0.71 in the control group, RW, % concentration of the UW, and 25% concentration of the UW, respectively. Plant growth was interrupted in the 50 and 100% concentrations of the UW and the mitotic division was inhibited. No anomalies were encountered in the control group. In the RW, a low rate of anomaly was observed, while in the different concentrations of the UW, chromosomal aberrations such as high frequency of lagging chromosome, irregular distribution, polar slips, horizontal division and sticky chromosome were observed.