A Review of Reclaimed Water Reuse for Irrigation in South Asian Countries

Despite having densely populated and highly water-stressed regions, wastewater treatment is limited in South Asia and its reuse for agriculture is mostly restricted to untreated or partially treated wastewater. Adequately treated wastewater or reclaimed water (RW) reuse for irrigation is mostly absent. Thus, this review examines the current status and challenges hampering RW reuse for irrigation in South Asia. In accordance with currently published literature, only India reuses RW for irrigation and has RW reuse guidelines. The other seven South Asian countries primarily reuse untreated wastewater for irrigation and do not have RW reuse guidelines. Institutional inefficiencies, limited research, economic and infrastructural deficiencies, and public resistance hinder the successful implementation of the RW reuse. A RW water quality guideline for the South Asian region is proposed based on the parameters of the Indian and international guidelines, which might also provide useful insights for other developing nations to develop their own economically and technologically feasible guidelines. Moreover, an outline for the preliminary feasibility study of sustainable RW reuse projects as well as explicit roles and responsibilities of stakeholders at various phases have been proposed as a decision-making tool for selective investment.