Water samples were collected from Tongi Khal (canal), Shitalakkhya river, and Dhalesdhwari river, situated in and around Dhaka, Narayanganj, and Gazipur (Figure 1). Two distinct points (one point for upstream and one point for downstream of the discharges) were selected for carrying out the surface water sampling at each of the three sampling sites. Both points were near the industrial establishments where the wastewater was discharged. More than 200 large and small factories are situated around Tongi canal out of which 48 run without an ETP (Halder & Sarker 2021). According to the Bangladesh Bureau of Statistics, there are 2,409 industry units present in Narayanganj (Narayanganj – Banglapedia n.d.). The wastewater coming from these industry units eventually ends up at the Tongi canal and Shitalakhya river. The coordinates of sampling locations are presented in Table 1.