This study examines the prospects for using Hydra viridissima toxicity test 96-h LC50, served as a model invertebrate, Lactuca sativa L. was applied for seeds toxicity test (120-h IC50) and a model plant for an acute toxicity assessment of heavy metals content in water. The heavy metals used to assess the acute toxicity of the water utilized for agricultural irrigation in arid regions includes cadmium (CdCl2.2H2O), chromium (K2Cr2O7), zinc (ZnSO4. 7H2O), and boron (H3BO3). A grading of the substances was conducted, and it was found that the toxicity levels for H. viridissima and L. sativa were, with the least harmful first: B < Cr < Zn < Cd and Zn < B < Cr < Cd, respectively. Results indicate that H. viridissima was a more sensitive indicator of toxicity for all of the evaluated substances. However, L. sativa could also be used successfully to rank toxicants in order of their potential hazards.