Rethinking Water: The Promise of Treated Wastewater Reuse in Agriculture in Lebanon is a brief / practical guidance note published by ESCWA as part of the Climate-Resilient Water Solutions in Jordan and Lebanon project, led by UN-Habitat in collaboration with ESCWA and UNICEF, and funded by the Adaptation Fund. It focuses on the safe reuse of treated wastewater for irrigation in Lebanon as a practical response to water scarcity, climate change, and agricultural pressures.
Key insights:
The brief explains that water scarcity is an urgent challenge in Lebanon, affecting farmers, food security, and rural livelihoods. At the same time, Lebanon produces large quantities of wastewater, much of which remains untreated or is discharged into the environment.
Although Lebanon is often seen as relatively water-rich compared with neighbouring countries, the brief stresses that this perception hides deeper problems, including poor water management, seasonal shortages, ageing infrastructure, and major water losses.
Lebanon’s renewable freshwater resources are estimated at around 780 cubic metres per person per year, which is below the water scarcity threshold of 1,000 cubic metres per person per year.
Around 50% of water is lost because of network leakage and inefficient management, while about 60% of irrigation water is extracted from groundwater sources.
Agriculture accounts for around 59% of freshwater withdrawals in Lebanon, making irrigation a central pressure point in the country’s water system.
The brief notes that excessive groundwater extraction contributes to falling water tables, soil salinization, and groundwater pollution, while the overuse of chemicals and fertilizers further harms soil and groundwater quality.
Climate change is intensifying these pressures by reducing snow cover, changing rainfall patterns, and increasing drought risks. These conditions can push farmers toward unsafe practices, including irrigation with polluted rivers or untreated wastewater.
The safe reuse of treated wastewater can help reduce pressure on freshwater resources, provide a reliable additional source of irrigation water, and protect rivers and groundwater from pollution.
Treated wastewater may also contain useful nutrients such as nitrogen, phosphorus, and potassium, which can reduce farmers’ spending on fertilizers.
The brief emphasizes that water quality must match crop type. Not all treatment plants produce water of the same quality, so treatment plant operators must monitor water quality and clearly inform farmers about safe uses.
Farmers also have a responsibility to ask about water quality before using treated wastewater, because quality determines which crops can be irrigated safely.
Lebanon’s standards body, LIBNOR, has introduced standards to guide safe reuse by defining water quality levels, appropriate crops, irrigation methods, and safeguards against germs, heavy metals, and salts.
The brief identifies three quality levels for treated wastewater. Level 1, the highest quality, comes from advanced treatment such as tertiary treatment, filtration, and disinfection, and can be used for raw vegetables grown above ground without direct contact and for public parks and gardens.
Level 2, medium quality, usually comes from secondary treatment and can be used for crops that are cooked or processed, such as wheat, potatoes, corn, carrots, fruits, fodder crops, and partly open gardens.
Level 3, the lowest quality, comes from primary treatment or simple sedimentation and should only be used for industrial crops, energy crops, ornamental plants, and gardens not open to the public.
The brief also stresses that irrigation method matters as much as water quality. Drip and subsurface irrigation are the safest methods for crops eaten raw and fruits eaten without peeling, because they reduce contact between water and edible parts of the plant.
Sprinklers are not allowed for raw crops or fruits eaten without peeling. In parks and green areas, only low-angle sprinklers are allowed to reduce spray drift.
The brief presents Zahle Wastewater Treatment Plant in the Bekaa Valley as a case study for treated wastewater reuse. The plant already existed, but the project added infrastructure and management components to improve reuse for irrigation.
The Zahle plant treats domestic wastewater through three stages: primary treatment to remove solids and debris, anaerobic treatment and aeration, and ultraviolet filtration for final disinfection.
The project added a balancing tank, pumping system, upper storage tank, and repaired solar energy system to reduce operating costs and improve sustainability. It also improved tertiary treatment by increasing the efficiency of ultraviolet disinfection.
A fair tariff of 18 to 20 cents per cubic metre was set to cover operation, staffing, and water testing costs, while remaining lower than many farmers’ current irrigation costs.
A Water Users Association was established to manage water distribution, collect fees, train farmers on safe irrigation practices, and strengthen local ownership of the system.
The Zahle treated-water irrigation system currently covers around one third of irrigation needs in the targeted agricultural area, with potential to supply larger quantities if the plant operates at full capacity.
Initial farmer concerns were addressed through workshops and training sessions. Environmental assessment helped identify crops that can be safely irrigated and encouraged the use of drip irrigation.
Main message: Treated wastewater reuse is a strategic opportunity for Lebanon. When properly treated, monitored, distributed, and matched with safe crop and irrigation choices, it can reduce pressure on freshwater resources, protect farmers from drought, lower irrigation costs, reduce pollution, and strengthen the resilience of agriculture and rural livelihoods in the face of climate change.
