Pressing water scarcity in Jordan rapidly increases the demands of marginal water resources for the agricultural sector. Water management studies reveal that no single source could fully solve the nation's water shortage and many integrated actions are needed to ensure water availability, suitability and sustainability. Yet, among these options treated wastewater has the largest potential to augment water supply in the near future, thereby narrowing the gap between available freshwater and total demand. Indeed, treated wastewater could be a valuable source for irrigation in the agricultural sector and an increasing percentage of irrigated areas, especially in the Jordan Valley, are currently using treated wastewater. With a fast growing population and expansion of the irrigated areas to meet food demand, the pressure on water resources in Jordan remains of imminent importance. Hence, an urgent call to analyze the current and potential role of treated wastewater seems justified. Under the umbrella of the project on the Sustainable Management of Available Water Resources with Innovative Technologies (SMART) funded by the German Federal Ministry for Education and Research in Germany, an investigation has been carried out in the Jordan Valley to estimate the current wastewater reuse quantities and the potential to increase its utility for agricultural production. In general, the reuse as percentage of total treatment is applied for national and international comparisons. Yet, this index is of limited use for policy decisions as it does not reflect potentialities of wastewater use. Therefore, this study introduces a wastewater reuse index (WRI) that reflects the actual proportion of wastewater reused from the total generated wastewater. We found that the WRI in Jordan steadily increased from 30% in 2004 to 38 in 2007. Efficient use of treated wastewater requires the application of new technologies in Jordan like dwellings connected to the sewer system, decentralization of treatment plants to rural and urban settlements and prevention of high evaporation rates from stabilization ponds. © 2011 Springer Science+Business Media B.V.