Irrigation with sewage effluent provides crops with water and nutrients. At the same time it provides a convenient means of sewage disposal through land treatment, preventing potential health and environmental hazards caused by the uncontrolled flow of wastewater. Under arid and semi-arid environmental conditions, in which irrigation is a prerequisite for agricultural development, the importance of effluent as a source of irrigation water is as great as the need for its disposal. Effluent becomes exceptionally valuable where other sources of water are scarce, and its utilization for irrigation frees high quality water for other uses. Therefore, there is considerable interest in the use of sewage effluent in dry regions, such as parts of southern and western USA, Australia, Mexico, and Israel. Land treatment methods for disposal purposes are employed under arid as well as humid climates (Bouwer and Chaney 1974; Pound et al. 1983; Page et al. 1983).