Saudi Arabia loses groundwater faster than nature can replace it — but a new study suggests the country’s massive surplus of treated wastewater could help refill depleted aquifers and secure long-term water supplies across one of the world’s driest regions.
Saudi Arabia is sitting on a water crisis hiding in plain sight. More than two-thirds of the country’s irrigation water and roughly a third of its drinking water come from underground aquifers — ancient reserves that are being drained far faster than rainfall can replenish them. At the same time, the country produces 1.6 billion cubic meters of treated wastewater every single year, most of which goes largely unused.
New research presented at the EGU General Assembly 2026 suggests those two problems may actually solve each other.
Mohammed Benaafi, a research scientist at King Fahd University of Petroleum and Minerals, and his colleagues investigated whether that surplus treated wastewater could be safely injected back into coastal aquifers through a process known as managed aquifer recharge — essentially using engineered systems to refill underground water supplies with treated water rather than waiting for natural precipitation to do the job.
A Resource Hiding in Plain Sight
The scale of the opportunity is striking. According to Benaafi, that 1.6 billion cubic meters of annually underutilized treated wastewater is equivalent to roughly 60% of Saudi Arabia’s total urban drinking water demand each year. Rather than treating it as waste to be discharged, Benaafi argues it should be viewed through an entirely different lens.
“It is a strategic asset that could be utilized for aquifer recharge,” Benaafi said in a news release.
The challenge, however, isn’t simply a matter of pumping wastewater into the ground. The quality of the treated water and the rate at which it is injected both play critical roles in determining whether the approach succeeds or backfires.
What the Lab Experiments Revealed
To test the concept under realistic conditions, Benaafi and his team conducted laboratory experiments comparing different treatment levels and recharge rates, then measured their effects on water flow through soil and on groundwater quality.
The results revealed a clear and important tradeoff. When lower-quality treated wastewater is injected at high recharge rates, the aquifer clogs more quickly — meaning the pores and channels that allow water to move through soil and rock become blocked, reducing the system’s effectiveness over time. But when higher-quality treated wastewater is introduced at lower, more controlled recharge rates, flow is maintained and the impact on groundwater quality is minimized.
In practical terms, the findings suggest that the process works — but only when it is carefully calibrated. Treatment quality and injection speed aren’t just technical footnotes; they determine whether an aquifer recharge project becomes a long-term solution or a costly mistake.
Why It Matters: Water Stress Is a Global Challenge
The implications extend well beyond Saudi Arabia’s borders. Arid and semi-arid regions around the world — from North Africa and the Middle East to parts of the American Southwest and Central Asia — face versions of the same dilemma: growing populations and agriculture are depleting groundwater reserves that took thousands of years to accumulate, while treated wastewater is routinely discarded.
The researchers calculate that with optimized treatment and recharge strategies, wastewater reuse could reduce groundwater withdrawals in eastern Saudi Arabia alone by almost a third. That would represent a significant easing of pressure on aquifers that currently have no viable path to natural recovery at current rates of use.
The use of treated wastewater in managed aquifer recharge “provides a sustainable solution to reduce the stress on nonrenewable groundwater and mitigate aquifer depletion in arid regions,” Benaafi added.
Benaafi’s framing of treated wastewater as a resource rather than a liability reflects a broader shift in thinking among water scientists and policymakers. As climate change continues to reduce freshwater availability and intensify droughts in already-dry regions, circular approaches to water management — where treated wastewater is systematically cycled back into supply — are gaining traction as a matter of necessity, not just preference.
What Comes Next
The research is being presented as a poster session during the EGU General Assembly 2026, taking place May 3–8 in Vienna, Austria.
For students studying environmental science, hydrology, civil engineering or public policy, this research represents exactly the kind of systems-level problem-solving that will define careers in the coming decades. Managed aquifer recharge sits at the intersection of water infrastructure, environmental regulation, public health and climate adaptation — and regions worldwide are increasingly desperate for affordable, scalable answers.
The work underscores a fundamental truth about resource scarcity: sometimes what looks like a waste problem is actually a supply problem in disguise.
Source: European Geosciences Union