Bioretention is one of best management practices (BMPs) for stormwater quantity and quality control. To date, there has been a great deal of research on bioretention system. Many studies have been conducted on the performance of single bioretention in terms of water quality improvement. The aim of this paper to evaluate WQI of the treated stormwater through column investigation in cascaded bioretention arrangement. Three set of models for Set A, Set B and Set C as a control column have been set up with identical column configuration. The WQI parameters including pH, DO, BOD, COD, NH3-N, and TSS, have been evaluated. The pH for Set A, Set B and Set C ranged between 6.92 to 6.98, 6.80 to 6.93 and 6.69 to 6.99 respectively. The DO increment varied from 6 to 21. All cascaded bioretention columns performed well for removal of BOD, NH3-N and TSS which were more than 80 except for COD was with the range of 66�72. Cascaded bioretention system performed significant removal of pollutants. The overall performance of the system for WQI was above 70. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.