Head-to-head: Water security & desalination — comparing leading approaches on cost, performance, and deployment

Global freshwater demand is projected to exceed supply by 40% by 2030 according to the United Nations World Water Development Report 2025, and North America is not immune. More than 50 million Americans currently live in water-stressed regions, with the Colorado River Basin alone facing a structural deficit of 3.2 million acre-feet per year. Desalination and advanced water treatment technologies have moved from niche coastal solutions to central components of municipal, industrial, and agricultural water security strategies. But the technology landscape is crowded, costs vary enormously by approach, and deployment trade-offs are poorly understood outside specialist circles. This head-to-head comparison breaks down what actually works, what it costs, and where the critical decision points lie.

Why It Matters

North America's water infrastructure deficit runs into hundreds of billions of dollars. The American Society of Civil Engineers estimated in its 2025 Infrastructure Report Card that the United States needs $625 billion in water infrastructure investment over the next decade, up from $434 billion in its 2021 assessment. California's Department of Water Resources projects that the state will need 3 to 4 million acre-feet of new or replacement supply by 2040 to maintain current service levels under median climate scenarios.

Desalination capacity in the United States has grown from approximately 1.6 billion gallons per day (BGD) in 2020 to 2.3 BGD in 2025, with another 1.1 BGD under construction or in advanced permitting (Global Water Intelligence, 2025). But desalination is only one piece of the puzzle. Potable water reuse, brackish groundwater treatment, atmospheric water generation, and advanced membrane filtration are all competing for capital allocation. Decision-makers at utilities, municipalities, and industrial facilities need to evaluate these approaches against consistent benchmarks to allocate scarce capital effectively.

Key Concepts

Water security technologies fall into several categories based on their feedwater source, energy intensity, and output quality. Seawater desalination converts ocean water (35,000 mg/L total dissolved solids, or TDS) into potable water. Brackish water desalination treats lower-salinity groundwater or surface water (1,000 to 15,000 mg/L TDS) at substantially lower energy cost. Direct potable reuse (DPR) and indirect potable reuse (IPR) treat municipal wastewater to drinking water standards. Advanced membrane technologies, including forward osmosis (FO) and membrane distillation (MD), represent emerging alternatives to conventional reverse osmosis (RO).

The critical performance metrics across all approaches are: energy consumption per unit of water produced (kWh/m3), capital expenditure per unit of installed capacity ($/m3/day), levelized cost of water (LCOW, $/m3), recovery rate (percentage of feedwater converted to product water), and concentrate management requirements.

Approach 1: Seawater Reverse Osmosis (SWRO)

Seawater reverse osmosis remains the dominant desalination technology globally, accounting for approximately 69% of installed desalination capacity worldwide (International Desalination Association, 2025). In North America, the Claude "Bud" Lewis Carlsbad Desalination Plant in San Diego County produces 50 million gallons per day (MGD) and remains the largest SWRO facility in the Western Hemisphere.

Energy consumption for modern SWRO plants ranges from 3.0 to 4.5 kWh/m3, down from 5 to 8 kWh/m3 in facilities built before 2010, driven primarily by improvements in energy recovery devices and membrane efficiency. Capital costs for large-scale SWRO (above 25 MGD) in North American markets typically fall between $4 to $7 per gallon per day of installed capacity, translating to $1,200 to $2,100 per m3/day (WaterReuse Research Foundation, 2025).

The LCOW for SWRO in the United States ranges from $1.50 to $2.80/m3 depending on plant scale, energy costs, and permitting complexity. For comparison, the Carlsbad plant delivers water at approximately $2,500 per acre-foot ($2.03/m3), while the proposed Doheny Ocean Desalination Project in Dana Point, California targets $1,900 per acre-foot ($1.54/m3) using subsurface intake technology that reduces pretreatment costs.

Recovery rates for SWRO typically range from 40 to 50%, meaning that 50 to 60% of intake seawater is returned as concentrated brine. Concentrate disposal is the primary environmental and regulatory challenge: the Carlsbad plant dilutes its concentrate with power plant cooling water discharge, but this co-location model is disappearing as coastal power plants retire. Standalone SWRO facilities must invest in diffuser systems, concentrate treatment, or zero-liquid discharge (ZLD) technologies that can add $0.30 to $0.80/m3 to costs.

Approach 2: Brackish Water Reverse Osmosis (BWRO)

Brackish water desalination treats feedwater with TDS levels ranging from 1,000 to 15,000 mg/L, requiring significantly less energy than seawater treatment. Energy consumption for BWRO ranges from 0.5 to 2.5 kWh/m3, roughly one-third to one-half that of SWRO. Capital costs are also lower, typically $1 to $3 per gallon per day of installed capacity.

The Kay Bailey Hutchison Desalination Plant in El Paso, Texas, the largest inland desalination facility in the world at 27.5 MGD, produces water at approximately $1.25/m3. Recovery rates for BWRO are higher than SWRO, typically 75 to 90%, reducing the volume of concentrate requiring disposal. However, inland concentrate disposal presents its own challenges: deep well injection, evaporation ponds, and beneficial use of concentrate all carry regulatory, environmental, and cost implications.

BWRO is geographically constrained by the availability of brackish aquifers. The United States Geological Survey estimates that brackish groundwater reserves in the western and southern United States could supply approximately 870 trillion gallons, a substantial resource that remains largely untapped. Texas, Florida, and California account for more than 60% of U.S. brackish desalination capacity (USGS, 2024).

The primary risk for BWRO is aquifer sustainability. Brackish aquifers are not always recharged at rates matching extraction, and long-term pumping can draw in higher-salinity water from adjacent formations, increasing treatment costs over time. The Brackish Groundwater National Desalination Research Facility in Alamogordo, New Mexico has documented TDS increases of 15 to 30% in some test wells over 10-year pumping periods (Bureau of Reclamation, 2025).

Approach 3: Potable Water Reuse (DPR and IPR)

Potable water reuse treats municipal wastewater through advanced treatment trains, typically including microfiltration, reverse osmosis, and ultraviolet/advanced oxidation, to produce water meeting drinking water standards. Indirect potable reuse (IPR) introduces treated water into an environmental buffer such as a groundwater basin or reservoir before distribution. Direct potable reuse (DPR) sends treated water directly into the distribution system or raw water supply.

Energy consumption for advanced water reuse ranges from 0.8 to 1.5 kWh/m3, substantially below SWRO and comparable to or below BWRO. Capital costs range from $2 to $5 per gallon per day. The LCOW for potable reuse in North American implementations ranges from $0.70 to $1.60/m3, making it the most cost-competitive option in many inland settings.

The Orange County Water District's Groundwater Replenishment System (GWRS) in California, the world's largest IPR facility at 130 MGD, produces water at approximately $1,200 per acre-foot ($0.97/m3). The facility has operated since 2008 with zero water quality violations and recently completed its final expansion. El Paso's Advanced Water Purification Facility, scheduled for full commissioning in 2027, will be the first large-scale DPR facility in the United States at 10 MGD.

Public acceptance remains the primary barrier to potable reuse. Surveys by the WateReuse Association in 2025 found that 60% of Americans support IPR after educational outreach, but only 38% initially support DPR without explanation. Utilities that invest in community engagement programs before and during facility development report significantly higher acceptance rates. The key regulatory development is California's adoption of DPR regulations in December 2023, which established a regulatory pathway that other states are expected to follow.

Approach 4: Emerging Technologies

Forward osmosis (FO) uses a draw solution with higher osmotic pressure than the feedwater to pull water across a semi-permeable membrane without applied hydraulic pressure. FO's theoretical energy advantage over RO has attracted significant research investment, but commercial deployment remains limited. Trevi Systems has piloted FO-based systems for industrial water treatment and oil and gas produced water, but municipal-scale applications remain in early demonstration stages. Energy consumption for FO systems currently ranges from 1.5 to 3.0 kWh/m3 when including the energy required to regenerate the draw solution, narrowing the gap with conventional RO.

Atmospheric water generation (AWG) extracts water vapor from ambient air using condensation or desiccant-based systems. While companies like SOURCE Global (formerly Zero Mass Water) have deployed hydropanel systems across 52 countries, the technology's energy intensity (250 to 680 kWh/m3 depending on humidity conditions) and low output volumes make it unsuitable for municipal-scale supply. AWG's role is limited to off-grid, point-of-use applications in remote communities or emergency response.

Electrodialysis reversal (EDR) offers advantages over RO for treating brackish water with high fouling potential or specific ion removal requirements. EDR operates at recovery rates of 85 to 95% and is particularly effective for waters with silica concentrations that challenge RO membranes. The technology is deployed at more than 30 municipal facilities across the United States, with the largest installations producing 5 to 15 MGD.

What's Working

Large-scale SWRO and potable reuse are both delivering reliable water supply in North America at costs that increasingly compete with traditional imported water. The Metropolitan Water District of Southern California's Regional Recycled Water Program, a planned 150 MGD IPR facility, will produce water at a projected $1,500 per acre-foot, well below the $2,000+ per acre-foot cost of imported State Water Project supplies. The combination of falling membrane costs (down 25 to 35% per unit area since 2018) and improving energy recovery has compressed the cost gap between desalination approaches and conventional supply.

Brackish water desalination in Texas has proven particularly effective, with the Texas Water Development Board reporting 46 operational BWRO plants in 2025 producing a combined 185 MGD at costs 30 to 50% below equivalent SWRO facilities.

What's Not Working

Zero-liquid discharge (ZLD) for inland desalination concentrate remains prohibitively expensive at $5 to $15/m3 of concentrate treated, limiting the scalability of BWRO in areas without viable deep well injection options. Permitting timelines for new coastal SWRO facilities in California continue to average 10 to 15 years due to California Coastal Commission review requirements, intake and discharge regulations, and environmental impact litigation. The proposed Huntington Beach SWRO plant was ultimately rejected in 2022 after a 20-year permitting process.

Emerging technologies including forward osmosis and atmospheric water generation have not achieved cost or scale parity with established approaches. Despite hundreds of millions of dollars in venture investment since 2018, no FO-based municipal desalination plant operates at scale in North America.

Key Players

Established: IDE Technologies (SWRO plant design and operation, including Carlsbad), Veolia Water Technologies (full spectrum water treatment and reuse), Xylem (pumping, treatment, and analytics for water utilities), DuPont Water Solutions (FilmTec RO and NF membranes), Toray Industries (membrane manufacturing for SWRO and BWRO)

Startups: Trevi Systems (forward osmosis for industrial water), SOURCE Global (atmospheric water generation hydropanels), Gradiant Corporation (brine treatment and ZLD solutions), Epic Cleantec (on-site water reuse systems for buildings), 374Water (supercritical water oxidation for wastewater)

Investors: Xylem Watermark (water technology impact investing), Burnt Island Ventures (water technology venture capital), Emerald Technology Ventures (cleantech including water), Breakthrough Energy Ventures (water-energy nexus solutions)

Action Checklist

• Conduct a source water assessment to determine whether seawater, brackish groundwater, or treated wastewater is the most available and cost-effective feedwater for your region
• Compare LCOW across at least three technology approaches using site-specific energy costs, permitting timelines, and concentrate disposal options
• Evaluate potable reuse as a first option for inland communities where concentrate disposal costs make desalination uneconomic
• Engage regulatory agencies early in project scoping to identify permitting requirements, particularly for DPR and coastal SWRO
• Assess brackish aquifer sustainability through multi-year test pumping before committing capital to BWRO facilities
• Include concentrate management costs in all financial models, adding 15 to 40% to base LCOW estimates for facilities without co-located discharge options
• Monitor California's DPR regulatory framework as a template for state-level regulations likely to emerge across the western United States by 2028

FAQ

Q: Which desalination approach offers the lowest cost per cubic meter in North America? A: Potable water reuse (IPR/DPR) offers the lowest LCOW at $0.70 to $1.60/m3, followed by brackish water RO at $0.80 to $1.80/m3, and seawater RO at $1.50 to $2.80/m3. However, the cost-optimal choice depends on feedwater availability, energy prices, concentrate disposal options, and permitting feasibility. Inland communities without access to seawater or brackish aquifers may find potable reuse their only viable new-supply option at any cost.

Q: How does energy consumption compare across approaches? A: BWRO requires 0.5 to 2.5 kWh/m3, potable reuse requires 0.8 to 1.5 kWh/m3, SWRO requires 3.0 to 4.5 kWh/m3, and atmospheric water generation requires 250 to 680 kWh/m3. For facilities powered by grid electricity in North America, SWRO's higher energy demand translates to approximately $0.30 to $0.45/m3 in energy costs at average industrial electricity rates, compared to $0.05 to $0.15/m3 for BWRO and reuse.

Q: What is the biggest barrier to scaling potable water reuse in the United States? A: Public perception, not technology, remains the primary barrier. The "toilet to tap" framing that dominated early media coverage continues to influence public opinion despite treatment systems that produce water exceeding all federal drinking water standards. Utilities that invest in transparent community engagement, facility tours, and long-term water quality monitoring data sharing consistently achieve 70%+ public support. California's adoption of DPR regulations in 2023 removed the regulatory barrier in the largest market, and Texas, Florida, Arizona, and Colorado are developing similar frameworks.

Q: Should industrial users evaluate desalination differently than municipal utilities? A: Yes. Industrial users often require specific water quality profiles (ultrapure water for semiconductor manufacturing, low-silica water for boiler feedwater) that may favor one technology over another regardless of LCOW. Industrial facilities also have more flexibility in concentrate management, as concentrate streams can sometimes be integrated into cooling systems, process water loops, or on-site evaporation systems. The decision framework should prioritize water quality specifications, reliability requirements, and integration with existing process water systems over raw LCOW comparisons.

Sources

• United Nations. (2025). World Water Development Report 2025: Water for Prosperity and Peace. Paris: UNESCO.
• American Society of Civil Engineers. (2025). 2025 Report Card for America's Infrastructure: Drinking Water and Wastewater. Reston: ASCE.
• Global Water Intelligence. (2025). DesalData: Global Desalination Plant Inventory and Market Forecast. Oxford: GWI.
• International Desalination Association. (2025). IDA Desalination and Reuse Yearbook 2025-2026. Topsfield: IDA.
• WaterReuse Research Foundation. (2025). Cost Analysis of Seawater Desalination in the United States: Updated Benchmarks and Projections. Alexandria: WateReuse.
• U.S. Geological Survey. (2024). Brackish Groundwater in the United States: Updated Assessment of Resources and Development Potential. Reston: USGS.
• Bureau of Reclamation. (2025). Brackish Groundwater National Desalination Research Facility: 10-Year Research Summary. Washington: U.S. Department of the Interior.
• WateReuse Association. (2025). Public Perception of Potable Reuse: National Survey Results and Communication Best Practices. Alexandria: WateReuse.