Water security is a hot topic all over the world, due to global warming, climate change, natural calamities such as droughts and floods, overuse of water, and other factors. Water issues have been scientifically investigated from several perspectives, namely institutional, economic, social, environmental, managerial, and technological. However, the technological aspects of irrigation and water supply for smallholder farmers in the Mediterranean region have not been adequately addressed. This paper explores irrigation and water supply technologies for smallholder farmers in the selected Mediterranean countries (Egypt, Malta, Morocco, and Portugal). The methods of analysis are literature review, fieldwork, and observation. The literature survey reveals that Mediterranean countries share many common features in terms of climate, water and land resources, and development issues. Nevertheless, the selected countries in the Mediterranean region (Egypt, Malta, Morocco, and Portugal) differ in terms of type of crops, water management regulations, labor force availability, financial sustainability, and economic approaches. These remarks signal the need for applying a specific approach in selecting a technology for irrigation and water supply according to the regional context. Additionally, the financial and economic perspectives of the three key technologies (i.e., SLECI, desalination technology, and engineering constructed wetlands) require further analysis.

The overgrowing water scarcity in Egypt should be the motive to develop alternative water resources. The article focuses on a technical review of the state-of-the-art water policies for the reuse of agricultural drainage water in irrigation worldwide and in Egypt, due to the increasing pace of implementing mega water projects. Satisfying future water demands in Egypt depends on better utilization and efficient use of the available water resources. Optimal water management, particularly the nonconventional water resources, is an essential prerequisite for the sustainable development of Egypt. The hypotheses examined are that the available quantities of agricultural drainage water in Egypt shall decrease and the quality of that drainage water shall improve. In the meantime, it is expected that soil and water salinity rates shall rise as a result of the multiple reuses of the drainage water and also due to the expansion of modern irrigation practice not only in the newly reclaimed desert lands but also in some old heavy soil lands. In addition, a technical review of the impacts of those changes above on the phenomenon of seawater intrusion in the northern parts of the Nile Delta is presented. It is concluded that the impact of the national water-saving, irrigation improvement projects, and expansion in land reclamation in the desert are inversely proportional to the resulting amount of agricultural drainage water in Egypt. That reduction is interpreted as about 20%, which needs further extensive applied research to verify. That amount might be compensated with the safe reuse of treated wastewater, with the due health safeguards. Accordingly, as stated in the NWRP2037, caution should be taken while projecting the future available agricultural drainage water for reuse in each geographic zone in Egypt.

In a context of increasing pressure on water resources and severe aridity; expansion in the reuse of naturally treated wastewater can be a viable and low-cost solution particularly for irrigation forests, green non-fruit trees, fabric crops, industrial oils, and non-edible raw crops. Wastewater treatment is increasingly recognized as a potential means in El-Wahat El-Bahariya in Egypt. However, investment decisions concerning the reuse of treated wastewater in irrigation needs to be justified in terms of financial and economic feasibility and profitability. Therefore, this research study aims to conduct a cost–benefit analysis (CBA) of an investment project “reuse treated wastewater in irrigation compared to other modes of water irrigation projects. The CBA results revealed that the cost of the initial investment for the production of treated water used for irrigating green non-fruit trees, Bamboo trees, and Cactus in Sekem El-Wahat, is economically efficient with 88% compared to the exploitation of aquifer groundwater for irrigating the same crops. That project allows for an economic gain of about 4,428.5 €/ha compared to the cost of producing aquifer ground water in Sekem Farm El-Wahat is estimated at 10,800 €/year. Substituting the use of aquifer ground water for irrigating crops with reuse of treated wastewater helps reducing energy consumption and offers great financial benefits to the beneficial communities. A net benefit of the reuse of treated wastewater project is largely positive with NPV equivalent to 4599 €/year with a medium economic efficiency (BCR) of about 0.44.