The number of success stories about the wastewater use for non-potable purposes increased significantly in the last decade due to technological advances, knowledge dissemination and increased necessity (natural and human-induced pressure on water systems). The intentional recharge of aquifers (independent of influent water quality) for later abstraction or ecological benefits is widely known as managed aquifer recharge (MAR). Sporadically, recharging the aquifers with treated wastewater via soil aquifer treatment (SAT) is mentioned as potential solution against water scarcity, especially in arid countries where water conservation is a necessity. Despite their obvious benefits, best practice examples of MAR/SAT systems using treated wastewater are not many due regulatory, cultural, technical and economic limitations. At the EU level, a major bottleneck is represented by the lack of a regulatory risk assessment framework while in some other countries, religious and cultural implications can slow down the SAT implementation. The absence of an adequate aquifer for storing the water or the costs associated with the wastewater collection, pre-treatment, and transport to the infiltration site represent further additional obstacles.

Nevertheless, presence of emerging contaminants in the municipal wastewaters and their potential micro-bacteriological contamination of the receiving aquifer can represent a reality and thus monitoring of wastewater should be constantly provided. Other wastewater types such as from food and beverage industries or industrial service waters (i.e. cooling process waters) could be excellent sources for SAT and MAR.

The present paper describes the state-of-the-art in wastewater use for groundwater recharge and discusses the opportunities and prospects for future development. Best-practise examples will be given, together with considerations on planning, operation and maintenance of such schemes.