To assess the ability of tall fescue (Festuca arundinacea) and grass pea (Lathyrus sativus) plant species in phytoremediation by the utilization of freshwater and urban wastewater, greenhouse experiments were conducted in 2018 and 2019 with three diesel-contaminated soil levels of 0, 1.5, and 3% w/w (DC, D1.5, D3, respectively). The maximum of soil diesel removal of tall fescue was by freshwater (54% (2018); 46% (2019)) and in the grass, the pea was by wastewater (44% (2018); 41% (2019)). A significant difference was observed in the amount of diesel removal by the plants at two levels of contamination, but the type of irrigation water had no significant effect. The plant growth decreased significantly by diesel increased in all treatments except D1.5 of tall fescue-2018 that led to better growth compared to the DC treatment. Diesel concentration had significant effects on the plant parameters (dry weight, height, color, time of flowering, and podding), but the types of water had no similar impact. Phytoremediation was considered an effective method to reduce soil contamination, but treated wastewater could not significantly improve phytoremediation performance. The correlation coefficient indicated that the diesel removal rate was positively correlated with the plant height and shoot dry weight (p < 0.01).