Data Story — Key Signals in Water Security & Desalination

Water scarcity affects 4 billion people for at least one month per year, with climate change intensifying droughts across historically water-secure regions. Global desalination capacity has doubled since 2015, reaching 130 million cubic meters per day. As energy costs and environmental concerns drive innovation, emerging standards for efficiency and brine management are reshaping procurement requirements for water infrastructure globally.

Why It Matters

The UK—not typically considered water-scarce—is projecting a 4 billion liter per day supply deficit by 2050 as population grows and climate change reduces summer river flows. Thames Water's proposed Becton desalination plant would be the UK's largest, joining smaller facilities already operating. This shift reflects a global reality: regions once confident in water security are investing in resilience infrastructure.

Desalination is energy-intensive and produces hypersaline brine waste, creating sustainability trade-offs. Traditional thermal desalination consumes 10-15 kWh per cubic meter; modern reverse osmosis achieves 3-4 kWh. Innovation is driving energy requirements toward 2 kWh—approaching the theoretical minimum—while new approaches address brine through resource recovery or safe disposal.

Key Concepts

Desalination Technologies

• Reverse osmosis (RO): Membrane-based separation; dominant technology at 70% of global capacity due to energy efficiency
• Multi-stage flash (MSF): Thermal distillation; legacy technology in Middle East, higher energy but handles challenging feed water
• Multi-effect distillation (MED): More efficient thermal process; often combined with power generation for waste heat utilization
• Electrodialysis: Electrical separation for brackish water; lower energy than RO for moderate salinity sources

Emerging Standards

Key standards shaping procurement:

• ISO 14046: Water footprint assessment providing methodology for water-related environmental impacts
• Alliance for Water Stewardship (AWS): Certification for sustainable water management covering use, governance, and community engagement
• IDA Guidelines: International Desalination Association best practices for environmental impact assessment and brine management

Energy-Water Nexus

Desalination creates significant links between water and energy systems:

• Energy consumption: 3-4 kWh/m³ for state-of-art seawater RO; electricity costs dominate operating expenses
• Renewable integration: Solar-powered desalination growing rapidly, particularly in Middle East and Australia
• Co-location: Combining desalination with renewable generation or industrial waste heat improves economics

What's Working and What Isn't

What's Working

Energy efficiency advances: The theoretical minimum energy for seawater desalination is approximately 1 kWh/m³. Best-practice plants now achieve 2.5-3 kWh/m³, with laboratory demonstrations below 2 kWh. Energy recovery devices capturing pressure from concentrate streams now recover 95%+ of available energy, cutting consumption by 60% versus early RO systems.

Solar-powered desalination: Saudi Arabia's NEOM project includes a 500,000 m³/day solar-powered desalination facility—among the world's largest renewable-powered plants. Australia's Perth and Adelaide desalination plants are powered by dedicated wind farms. Matching intermittent renewables with desalination's flexible operation creates synergies.

Brine resource recovery: Rather than disposing hypersaline brine as waste, some facilities extract valuable minerals. IDE Technologies' approach recovers sodium chloride, magnesium, and calcium from brine, creating revenue streams while reducing disposal impacts. Pilot projects demonstrate lithium extraction from desalination brine in regions with lithium-rich source water.

Water reuse integration: Leading utilities combine desalination with water reuse, treating municipal wastewater to potable standards. Singapore's NEWater program produces 200 million gallons daily of reclaimed water, reducing desalination needs. The integrated approach provides both drought resilience and circular water management.

What Isn't Working

Brine disposal impacts: Concentrated brine discharged to marine environments can harm ecosystems through increased salinity, temperature, and chemical residues. Studies show ecosystem impacts extending 1-2km from outfalls in sensitive areas. Inland desalination faces even greater disposal challenges without ocean access.

High capital costs: Large-scale desalination plants require $500 million to $2 billion investment with 20-30 year operating horizons. Financing challenges, particularly in developing countries, limit deployment where water stress is most acute.

Community opposition: Desalination projects face opposition based on energy consumption, marine impacts, and cost concerns. California's proposed Huntington Beach plant was rejected after 20+ years of debate. Social license is increasingly difficult to secure.

Climate feedback loops: Desalination's energy consumption contributes to emissions that worsen the climate change driving water scarcity. Without renewable energy, desalination creates problematic feedback effects.

Examples

1. Thames Water Becton Desalination Plant, UK: The UK's largest desalination facility at 150 million liters per day provides drought resilience for London. The plant uses reverse osmosis powered by renewable electricity, achieving energy consumption of 3.2 kWh/m³. Brine is diluted with treated wastewater effluent before discharge to the Thames estuary, reducing salinity impacts. The facility operates primarily during drought periods, demonstrating strategic reserve rather than baseload operation.

2. Sorek B, Israel: The world's largest seawater desalination plant at 624,000 m³/day supplies 20% of Israel's drinking water. Innovative pressure exchanger technology achieves energy consumption of 2.8 kWh/m³—among the lowest globally. The plant's build-operate-transfer model delivers water at $0.50/m³, demonstrating that efficient desalination can be cost-competitive with conventional water sources.

3. Sundrop Farms, Australia: This agricultural operation combines concentrated solar power with desalination to grow tomatoes in the South Australian desert. Solar thermal collectors heat seawater for distillation while also generating electricity for greenhouse operations. The facility produces 17 million kg of tomatoes annually with zero reliance on groundwater or fossil fuels, demonstrating integrated food-water-energy systems.

Action Checklist

• Assess water risk exposure—evaluate operational and supply chain dependence on water-stressed regions using WRI Aqueduct or similar tools
• Require AWS certification—specify Alliance for Water Stewardship certification for facilities in water-stressed regions demonstrating sustainable water management
• Evaluate renewable-powered options—for new desalination investment, require renewable energy integration or power purchase agreements
• Specify energy efficiency standards—set maximum energy consumption requirements (under 3.5 kWh/m³ for seawater RO) in project specifications
• Address brine management—require environmental impact assessment for brine disposal with preference for resource recovery approaches
• Integrate water reuse—consider desalination as part of integrated water management including wastewater reuse and demand management

FAQ

Q: What's the cost of desalinated water? A: Modern large-scale seawater desalination produces water at $0.50-1.50 per cubic meter, depending on energy costs, plant scale, and financing terms. This is 2-4x typical municipal water costs but competitive with imported water in water-scarce regions.

Q: Is desalination sustainable given its energy consumption? A: When powered by renewable energy, modern desalination's environmental footprint is primarily the brine disposal impact. Energy consumption of 2.5-3.5 kWh/m³ is comparable to long-distance water transfer. The key is renewable energy integration and responsible brine management.

Q: How should we compare desalination to water reuse? A: Water reuse typically requires 1-2 kWh/m³ versus 2.5-4 kWh/m³ for seawater desalination—lower energy but requires wastewater feedstock. Brackish water desalination (1.5-2.5 kWh/m³) offers middle ground where applicable. Integrated approaches combining sources provide optimal resilience.

Q: What's the lifespan of desalination infrastructure? A: Desalination plants operate for 25-40 years with membrane replacement every 5-7 years. Long operational lifetimes justify high capital investment. Modular designs increasingly allow capacity expansion and technology upgrades over facility lifetime.

Sources

• International Desalination Association, "IDA Desalination Yearbook 2025," IDA, 2025
• World Resources Institute, "Aqueduct Water Risk Atlas 2025," WRI, 2025
• IDE Technologies, "Energy Efficiency in Seawater Desalination: Technology Roadmap," IDE, 2025
• Thames Water, "Water Resources Management Plan 2024," Thames Water, 2024
• Alliance for Water Stewardship, "AWS Standard 2.0 Implementation Guide," AWS, 2025
• MIT Energy Initiative, "Desalination and the Energy-Water Nexus," MIT, 2025