Scarcity of freshwater is becoming an increasing problem in Nigeria, hence, the need to explore other sources of water such as greywater for irrigation purposes. This study was conducted to investigate the effects of treated greywater on some growth parameters of pepper in Akure, Nigeria. Raw greywater was collected from Jadesola Female Hostel, Federal University of Technology, Akure (FUTA), Nigeria and pre-treated via a 500 litres sedimentation tank containing different layers of gravel and fine sand, and was released into a Vertical Flow Sub-surface Constructed Wetland (CW) with common reed planted on it, for actual treatment. The raw and treated greywater were analyzed to assess their conformity with irrigation water requirements. Raw greywater (RGW), Treated greywater (TGW) and Fresh water (FW) were used for irrigation of pepper in a randomized complete block design of three treatments and three replicates during the 2016, 2017 and 2018 dry seasons. Results showed average increase in plant height (PH), stem diameter (SD) and leaf area index (LAI) for the three seasons as 43.65 (FW), 31.07 cm (TGW) and 7. 41 cm (RGW), 1.93 cm (FW), 1.68 cm (TGW) and 1.05 cm (RGW); 7836.67 (FW), 3798.67 (TGW) and 2065.67, respectively. Application of Turkey HSD statistical package on the data obtained showed that both physiological and biochemical properties of treated greywater used as irrigation water have significant effects on such growth parameters as plant height (PH), stem diameter (SD) and leaf area index (LAI), at 5% probability value. Consequently, it was concluded that TGW has the potential to positively affect some growth parameters of pepper which themselves affect yield. Hence, TGW is recommended to farmers, especially pepper growers, for supplemental irrigation during short duration drought and full irrigation during dry season farming
