Water Infrastructure in Riyadh: Desalination, Distribution, and the Engineering of Abundance in a Desert Capital

Of all the infrastructure challenges that underpin Riyadh’s preparation for Expo 2030, none is more fundamentally existential than water. Riyadh sits in one of the most water-scarce regions on earth—the central Najd Plateau of the Arabian Peninsula, where annual rainfall averages less than 100 millimeters and where no permanent rivers or freshwater lakes exist within hundreds of kilometers. Every drop of water consumed in this city of 8-million-plus residents—and in the metropolitan area projected to reach 15 to 20 million by 2030—must be either extracted from rapidly depleting underground aquifers or manufactured through the energy-intensive process of desalinating seawater and pumping it hundreds of kilometers across the desert. The story of Riyadh’s water infrastructure is the story of engineering defiance of geography, and it is a story that becomes dramatically more complex when the city prepares to welcome 42 million visitors to the most expensive World Expo in history.

The Fundamental Challenge: Water in the Arabian Desert

Saudi Arabia is among the most water-scarce countries on the planet. The kingdom has no permanent rivers, no significant natural freshwater lakes, and receives an average of less than 100 millimeters of rainfall annually across most of its territory—compared to approximately 1,200 millimeters in the United Kingdom or 850 millimeters in the United States. The Arabian Peninsula’s geological and climatic conditions create a water equation that is fundamentally hostile to large-scale urban development.

Historically, Saudi settlements were limited to oases—locations where underground water reached the surface or was accessible through shallow wells. Riyadh itself originated as an oasis settlement, with the Wadi Hanifah providing seasonal water flow and shallow aquifers supporting date palm cultivation and small-scale agriculture. The transformation of this oasis settlement into a metropolitan region of 8 million people—and the ambition to grow it to 15 to 20 million—represents one of the most extreme examples of technology-enabled urbanization in human history.

The kingdom’s water supply comes from three primary sources: desalinated seawater (approximately 60 percent of total supply), groundwater extraction from nonrenewable fossil aquifers (approximately 35 percent), and treated wastewater reuse (approximately 5 percent and growing). The proportion of desalinated water has increased steadily as groundwater reserves have been depleted, and the long-term trajectory is toward even greater dependence on desalination—a trend that makes water supply inseparable from energy supply.

Desalination: Manufacturing Water at Industrial Scale

Saudi Arabia operates the largest desalination program in the world, and the Saline Water Conversion Corporation (SWCC) is among the world’s largest desalination operators. The kingdom’s desalination plants, located primarily on the Red Sea and Arabian Gulf coasts, produce billions of liters of freshwater daily using a combination of multi-stage flash distillation (MSF), multi-effect distillation (MED), and reverse osmosis (RO) technologies.

The desalination capacity has expanded dramatically under Vision 2030, with new plants commissioned and existing plants upgraded to meet growing demand. The shift toward reverse osmosis technology has been a key trend—RO is significantly more energy-efficient than thermal desalination processes, consuming approximately 3-5 kilowatt-hours per cubic meter of water produced compared to 10-20 kWh for thermal processes. This energy efficiency improvement is critical in a country where the energy cost of water production represents a significant fiscal burden.

For Riyadh, desalinated water must travel a long distance. The nearest coastline—the Arabian Gulf to the east—is approximately 400 kilometers from the capital. The Red Sea coast to the west is even farther. Massive pipeline systems transport desalinated water from coastal plants to Riyadh, with pumping stations at intervals to maintain pressure across the vast distances and significant elevation changes involved. The Jubail-Riyadh water transmission system is one of the world’s longest water pipelines, moving millions of cubic meters of desalinated water across the desert to supply the capital.

The energy cost of this system is substantial. Desalination itself is energy-intensive, and the pumping of water over hundreds of kilometers and over elevation changes of several hundred meters adds significantly to the energy requirement. The total energy cost of delivering a cubic meter of desalinated water to a consumer in Riyadh is estimated to be among the highest in the world—a cost that is subsidized by the Saudi government and that represents a hidden fiscal burden of the kingdom’s urbanization model.

The Expo Site: Water and Sewage Systems

The Expo 2030 site’s water infrastructure is being delivered as part of the Main Utilities and Infrastructure Works contract awarded to Nesma & Partners in late December 2025. The contract scope includes approximately 50 kilometers of critical utilities networks, explicitly including water and sewage systems alongside electrical, communications, EV charging, and internal road infrastructure.

The water demand at the Expo site will be driven by several factors: visitor consumption (drinking water, sanitation facilities, food preparation), landscaping and greenery maintenance (including the environmental regeneration of Wadi Al Sulai), cooling systems (which in Riyadh’s climate consume significant water volumes), fire suppression systems, and the operational needs of 226 pavilions, restaurants, retail outlets, and event spaces.

The peak daily water demand for a venue expecting hundreds of thousands of visitors is enormous. Drawing on the experience of previous expos and mega-events, water infrastructure design typically plans for peak demands that can be several times the average daily consumption, accounting for the variation between high-attendance and low-attendance days, time-of-day peaks, and the contingency requirements for fire suppression and emergency scenarios.

The sewage system must handle corresponding volumes of wastewater, with treatment capacity sufficient to process the combined wastewater from all visitor facilities, food service operations, and other sources. The treatment of this wastewater—potentially for reuse in irrigation, cooling, or other non-potable applications—represents an opportunity to demonstrate the sustainable water management practices that the Expo’s theme of “Sustainable Solutions” promotes.

The design of the water and sewage networks follows the detailed masterplan being developed by Buro Happold, with the infrastructure being installed by Nesma & Partners under Bechtel’s project management oversight. The network design must be robust enough to handle peak demands, redundant enough to maintain service if individual components fail, and flexible enough to support the site’s post-Expo transformation into a permanent residential and cultural neighborhood.

Wadi Al Sulai: Environmental Water Restoration

One of the most distinctive features of the Expo 2030 site plan is the environmental regeneration of Wadi Al Sulai, a restored riverbed that forms a central natural feature of the venue. The wadi—an Arabic term for a valley or channel that is dry except during rainfall—will be restored as a landscape element that integrates water features, native vegetation, and recreational spaces into the Expo experience.

The Wadi Al Sulai restoration represents an intersection of water infrastructure and environmental design. The creation of a functioning watercourse or water feature in a desert environment requires a dedicated water supply (likely treated wastewater or recycled water), a circulation and treatment system to maintain water quality, and a landscape design that incorporates drought-adapted native plants alongside the water features.

The project draws on Saudi Arabia’s growing experience with urban water landscaping, including the Green Riyadh initiative—a program to plant millions of trees across the city and create urban green corridors that reduce the heat island effect and improve air quality. Green Riyadh has demonstrated that significant landscaping is achievable in the Riyadh climate with appropriate species selection and irrigation technology, though the ongoing water requirements of such landscaping represent a permanent operational cost.

Groundwater: The Depleting Safety Net

While desalination is Riyadh’s primary water source, groundwater extraction continues to play a significant role in the kingdom’s water supply. Saudi Arabia sits atop several major aquifer systems, including the Saq, Tabuk, Wajid, Minjur, and Biyadh aquifer formations. These aquifer systems contain significant volumes of “fossil water”—groundwater that accumulated thousands of years ago during wetter climatic periods and that is not being replenished at any meaningful rate by current rainfall.

The depletion of these aquifer systems is one of Saudi Arabia’s most serious long-term environmental challenges. Decades of extraction for agriculture, industry, and municipal supply have drawn down water tables significantly. The Saq aquifer system, which historically supplied much of Riyadh’s water, has experienced declining water levels that have required progressively deeper drilling and more powerful pumping. The economic and environmental costs of continued depletion are substantial—deeper extraction requires more energy, and the depletion of aquifer systems can cause land subsidence, reduced water quality, and the eventual exhaustion of the resource entirely.

The Saudi government has recognized the unsustainability of continued heavy groundwater extraction and has implemented policies to reduce agricultural water consumption (historically the largest demand category), improve water use efficiency, and shift demand to desalinated sources. The phaseout of water-intensive wheat cultivation, which consumed enormous volumes of groundwater, was a significant policy step. However, the transition away from groundwater dependence is a multi-decade process, and in the interim, the aquifer systems continue to be drawn down.

For Expo 2030, the groundwater dimension is relevant primarily as context for the kingdom’s broader water security challenge. The Expo itself will draw its water from the desalination-fed municipal supply rather than directly from aquifers. But the sustainability narrative that the Expo promotes—the sub-theme of “Sustainable Solutions”—inevitably invites scrutiny of the host country’s management of its own most critical natural resource.

Treated Sewage Effluent: The Circular Economy

Saudi Arabia has invested significantly in wastewater treatment and reuse, recognizing that treated sewage effluent (TSE) represents a valuable water resource that can reduce demand on desalinated and groundwater supplies. TSE is used primarily for irrigation of parks, landscaping, and agricultural applications, as well as for industrial cooling and other non-potable purposes.

Riyadh’s wastewater treatment infrastructure includes multiple treatment plants that process the city’s sewage to standards suitable for various reuse applications. The treated effluent is distributed through a separate pipe network—distinct from the potable water system—to major landscaping projects, parks, and other irrigation consumers.

The expansion of TSE reuse is a key element of Saudi Arabia’s water sustainability strategy. By treating and reusing wastewater rather than discharging it, the kingdom both reduces its demand for desalinated water and avoids the environmental impact of wastewater discharge. The economic logic is compelling: the energy cost of treating wastewater to reuse standards is typically lower than the energy cost of desalinating an equivalent volume of seawater, and the avoided cost of long-distance pumping from coastal desalination plants is significant.

For the Expo 2030 site, TSE reuse could support the landscaping requirements of the venue, including the Wadi Al Sulai restoration, the public realm greenery, and the cooling water requirements of the venue’s climate management systems. Incorporating TSE reuse into the Expo’s water infrastructure would serve both practical purposes—reducing the venue’s demand on the desalinated water supply—and demonstrative purposes, showcasing circular economy approaches to water management that align with the Expo’s sustainability themes.

Distribution Network: Getting Water to Every Tap

The distribution network that delivers water to Riyadh’s millions of consumers—and that must extend to serve the Expo site and its millions of visitors—is a complex system of trunk mains, distribution mains, service connections, storage reservoirs, and pumping stations. The network must maintain adequate pressure and flow throughout the system, accommodate daily and seasonal variations in demand, and provide fire flow capacity for emergency situations.

Riyadh’s water distribution network has grown incrementally over decades, with successive expansions to serve new development areas. The quality and reliability of the network varies across the metropolitan area, with newer developments generally served by more modern infrastructure and older areas sometimes experiencing pressure problems, leakage, and service interruptions.

Water loss through leakage—known as non-revenue water—is a significant issue for Riyadh’s distribution network, as it is for many large-city water systems globally. Leakage rates in developing-country water systems can range from 20 to 40 percent of water entering the network, representing an enormous waste of a resource that is costly to produce. The Saudi government has invested in leak detection technology, network rehabilitation, and metering improvements to reduce non-revenue water, but the challenge of maintaining a vast and aging distribution network in a desert environment—where soil conditions and temperature extremes stress pipe materials—is ongoing.

The extension of the distribution network to serve the Expo site represents a new-build opportunity to install state-of-the-art infrastructure, including modern pipe materials, smart metering, leak detection sensors, and pressure management systems. The Expo site’s water network can serve as a demonstration of best-practice water distribution technology, which would align with the event’s theme of technological innovation.

Water Pricing and Conservation

Water pricing in Saudi Arabia has historically been heavily subsidized, with consumers paying well below the true cost of water production and delivery. This pricing structure has contributed to high per capita water consumption—Saudi Arabia’s per capita water use is among the highest in the world, reflecting both climatic conditions (high temperatures increase water demand for cooling, bathing, and landscaping) and the absence of price signals that would encourage conservation.

Vision 2030 included reforms to utility pricing, with gradual increases in water tariffs designed to reduce subsidies and encourage more efficient water use. The introduction of tiered pricing—where the per-unit cost of water increases at higher consumption levels—has been implemented in some areas, creating a financial incentive for conservation by large consumers while maintaining affordable rates for basic consumption.

For the Expo 2030 venue, water conservation measures will be both a practical necessity and a thematic requirement. Water-efficient fixtures, smart irrigation systems, rainwater harvesting (limited in utility given Riyadh’s low rainfall but symbolically important), and the reuse of greywater and treated effluent can all contribute to reducing the venue’s water footprint. These measures demonstrate the kingdom’s commitment to the sustainable water management practices that Vision 2030 and the Expo theme promote.

The Long-Term Water Equation

The water infrastructure supporting Expo 2030 Riyadh exists within a long-term water equation that is among the most challenging faced by any major city on earth. The combination of extreme aridity, rapid population growth, high per capita consumption, dependence on energy-intensive desalination, and the depletion of fossil aquifers creates a water security challenge that will intensify over the coming decades.

Climate change is expected to exacerbate these challenges. Rising temperatures increase water demand for cooling and human consumption while reducing the already minimal rainfall. Higher sea surface temperatures may affect the efficiency and cost of coastal desalination plants. The increasing energy cost of water production and delivery will place growing fiscal pressure on a government that is simultaneously managing oil revenue volatility and massive infrastructure investment programs.

The expansion of desalination capacity, powered increasingly by renewable energy sources (solar in particular, given Saudi Arabia’s exceptional solar resource), represents the most probable trajectory for meeting Riyadh’s long-term water needs. The Saudi government has announced ambitious plans for solar-powered desalination, and pilot projects have demonstrated the technical feasibility of coupling solar generation with reverse osmosis desalination. If this technology pathway is pursued at scale, it could fundamentally alter the energy economics of desalination and improve the sustainability of the kingdom’s water supply.

The Expo 2030 period represents a moment when the world’s attention will be focused on Riyadh—and when the kingdom’s management of its most fundamental resource will be on display. The water infrastructure that supports the Expo must do more than deliver adequate supply to the venue. It must demonstrate that Saudi Arabia is addressing its water challenge with the same ambition and capability that it brings to its airport expansion, its metro system, and its economic diversification. The engineering of water abundance in the desert is perhaps the most impressive—and most precarious—achievement that underpins the kingdom’s entire urban development model.