Water scarcity is among the most critical environmental and socio-economic challenges confronting Algeria. Located largely within arid and semi-arid climatic zones, the country experiences highly variable rainfall, frequent droughts, and limited renewable freshwater resources. Per capita renewable water availability in Algeria is estimated at around 404 m³/year, placing the country well below the internationally recognized water scarcity threshold of 1,000 m³/year [1]. Climate change projections indicate further reductions in precipitation, rising temperatures, and increased evapotranspiration, all of which are expected to intensify water stress in the coming decades [2]. In this context, the search for alternative and non-conventional water resources has become a national priority, with treated wastewater increasingly recognized as a strategic option for enhancing water security.
Globally, treated wastewater reuse has emerged as a key component of integrated water resources management, particularly in water-scarce regions. Wastewater is no longer viewed solely as a waste product but rather as a reliable and climate-resilient water source that can supplement conventional supplies [3]. In the Middle East and North Africa region, municipal wastewater generation is estimated at more than 20 billion cubic meters per year, yet only a fraction of this volume is safely treated and reused [4]. Expanding wastewater reuse can significantly reduce pressure on surface water and groundwater resources while supporting agricultural production, industrial activities, and environmental protection.
Algeria has made considerable investments in wastewater treatment infrastructure over the past two decades. More than 230 wastewater treatment plants have been constructed across the country, increasing the national treatment capacity substantially [5]. These facilities are distributed across coastal, high plateau, and southern regions, reflecting a national effort to improve sanitation coverage and reduce pollution loads discharged into the environment. Despite these investments, the actual reuse of treated wastewater remains limited. Estimates suggest that less than 10% of treated effluent is currently reused, primarily for agricultural irrigation, while the majority is discharged into wadis or the sea [6]. This gap between treatment capacity and reuse highlights a significant untapped potential.
Agriculture represents the most promising sector for wastewater reuse in Algeria. The sector accounts for the largest share of national water withdrawals and is particularly vulnerable to water shortages. In arid and semi-arid regions, irrigation relies heavily on overexploited groundwater resources, leading to declining water tables and increasing salinity [7]. Treated wastewater offers a dependable alternative supply for irrigation, especially for forage crops, cereals, industrial crops, and tree plantations. Studies conducted in several Algerian regions, including the Mitidja Plain and the M’Zab Valley, have shown that treated wastewater can be used for irrigation without significant adverse effects on soil or crops when appropriate treatment levels and management practices are applied [8-9]. Moreover, treated wastewater contains nutrients such as nitrogen and phosphorus, which can partially substitute for chemical fertilizers and reduce production costs.
Beyond agriculture, treated wastewater can support other water-intensive activities. Industrial reuse is increasingly recognized as a viable option, particularly for cooling, washing, and process water in industries where potable quality is not required. International experience shows that industrial reuse can significantly reduce freshwater demand and improve overall water efficiency [10]. In Algeria, where industrial development is expanding, especially in coastal and high-plateau regions, reclaimed wastewater could provide a reliable supply while reducing competition with domestic and agricultural water uses. Similarly, treated wastewater can be used for landscape irrigation, green belts, road cleaning, and dust control, contributing to improved environmental quality and urban livability without consuming valuable freshwater resources.
The role of treated wastewater in climate change adaptation is particularly relevant for Algeria. Climate change is expected to increase the frequency and severity of droughts, making traditional water sources less reliable [11]. Unlike rainfall-dependent resources, wastewater generation is closely linked to population size and water consumption patterns, making it a relatively stable supply even during dry periods. By integrating wastewater reuse into national water planning, Algeria can enhance the resilience of its water systems to climate variability. Furthermore, wastewater reuse aligns with circular economy principles by closing water loops, reducing pollution, and promoting resource efficiency [12].
Despite its potential, several barriers hinder the large-scale adoption of wastewater reuse in Algeria. Technical challenges include the limited availability of tertiary treatment processes, which are often required to meet reuse standards, particularly for unrestricted irrigation. Many treatment plants operate with primary or secondary treatment only, resulting in variable effluent quality [6]. Institutional and regulatory challenges also persist. While Algeria has established regulations governing wastewater reuse, enforcement and monitoring remain inconsistent, and coordination among water, agriculture, and environmental authorities is often limited [5]. In addition, public perception and social acceptance pose significant challenges. Concerns about health risks and environmental impacts can reduce willingness among farmers and communities to use reclaimed water, underscoring the need for transparent communication, capacity building, and stakeholder engagement.
Economic considerations further influence the feasibility of wastewater reuse. Although reuse can be cost-effective compared to alternatives such as desalination or long-distance water transfers, initial investments in treatment upgrades, distribution networks, and monitoring systems can be substantial. However, studies in comparable arid regions demonstrate that the long-term economic benefits of wastewater reuse including reduced water scarcity impacts, improved agricultural productivity, and job creation, often outweigh the costs [4,10]. In Algeria, targeted financial incentives, public–private partnerships, and integration of reuse into agricultural and industrial development programs could accelerate adoption.
Treated wastewater should not be viewed as a standalone solution to Algeria’s water scarcity but rather as a complementary component of a diversified water portfolio. The country has invested heavily in seawater desalination to secure drinking water supplies, particularly in coastal regions. While desalination provides a reliable source of potable water, it is energy-intensive and costly. Combining desalination with wastewater reuse allows for a more balanced allocation of resources, reserving high-quality desalinated water for domestic use while employing reclaimed wastewater for non-potable applications [13]. Such an integrated approach enhances overall system efficiency and sustainability.
Conclusion
The treated wastewater has significant potential to help Algeria overcome its growing water scarcity. The existing wastewater treatment infrastructure provides a strong foundation, but greater efforts are needed to translate treatment capacity into effective reuse. By upgrading treatment technologies, strengthening regulatory frameworks, promoting stakeholder acceptance, and integrating wastewater reuse into broader water and climate strategies, Algeria can transform wastewater from an underutilized by-product into a strategic resource. While wastewater reuse alone cannot fully resolve water scarcity, it is an essential pillar of sustainable water management and a key contributor to long-term water security in Algeria.
References
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