Seawater desalination: the sector structure, who makes money, and where the niche opportunities are

Freshwater is not running out globally, but accessible freshwater is running short in specific regions — the Middle East, North Africa, coastal India, parts of Southeast Asia, and the American Southwest — and the gap between where water falls and where people live is structural, not cyclical. Desalination is one of the few technologies that addresses this gap at scale. Understanding how the industry works, who earns money from it, and where margins concentrate is useful context both for the sector itself and for evaluating the equipment companies that serve it.

How SWRO works, and why energy recovery matters

Seawater reverse osmosis pushes seawater at very high pressure (typically 55 to 80 bar) through semi-permeable membranes that allow water molecules through but reject dissolved salts. The output is purified permeate water and a high-pressure brine reject stream. The membranes do the chemistry; the pressure does the work.

Energy is the dominant operating cost in any SWRO plant — typically 30 to 50 percent of total cost of water produced. The reason is that creating and sustaining 800 pounds per square inch of pressure across millions of gallons of seawater per day requires continuous power input from high-pressure pumps.

In the early decades of SWRO, that energy was simply expended: the brine reject stream, still carrying most of the pump's pressure, was vented to the ocean. Energy recovery devices changed this. A pressure exchanger captures the kinetic energy of the high-pressure brine and transfers it directly to the incoming seawater feed — without electricity, without moving parts that require scheduled maintenance, at efficiencies above 95 percent. This single addition cut the energy intensity of SWRO by up to 60 percent, which is what made the technology economically viable at scale and enabled it to displace thermal desalination (multi-stage flash and multi-effect distillation) as the industry standard.

The value chain

A desalination project runs through several layers of supply:

EPC contractors engineer, procure, and construct the plant. These are the largest line items on a project budget — civil works, structural steel, piping, electrical, instrumentation. EPC is competitive and margin-thin: large international contractors (Veolia, ACCIONA Agua, IDE Technologies, and others) bid against each other on price. The revenue is lumpy (project-by-project), the margins are low single digits, and the pricing power is minimal. An EPC firm wins on price, relationships, and execution track record. It does not win on proprietary technology.

Membrane manufacturers make the semi-permeable membranes that actually perform the salt rejection. DuPont (FilmTec brand), Toray, and a handful of others dominate here. Membranes degrade over time and need periodic replacement — typically every five to ten years depending on feedwater quality and operating conditions. That creates an aftermarket: once a plant is built around a particular membrane specification, the operator has a strong preference for like-for-like replacement rather than requalifying a different supplier's membranes across an entire array. Membrane manufacturers have recurring replacement revenue and moderate switching costs once a plant is operational.

High-pressure pump manufacturers provide the equipment that generates the pressure. Large pump suppliers — Grundfos, Sulzer, and others — compete here. Pumps are specified at the design stage, and like membranes, replacement and spare parts tend to go back to the original supplier. Switching costs exist but are lower than membranes because pump performance specs are more standardized.

Energy recovery device manufacturers make the pressure exchangers. This is the narrowest and most defensible layer of the supply chain. The device is integrated into the plant's hydraulic design at the engineering stage; replacing it requires replumbing and rebalancing the entire pressure circuit. The installation base, once created, tends to be sticky. Aftermarket revenue — spare parts, upgrades, and refurbishments — accrues at high margin because the alternative for the operator is a plant redesign, not a product swap.

Chemicals and consumables (antiscalants, cleaning agents, biocides) are consumed continuously. This layer is fragmented and competitive, with limited pricing power at the supplier level.

Where margins concentrate

The pattern across the supply chain is consistent: the higher the switching cost and the more embedded the product is in the plant's operating chemistry or hydraulics, the higher the margin. EPC is at one end — fully commoditized, competitive bidding, thin margins. Membranes and energy recovery devices are at the other — engineered components, switching friction, recurring replacement demand, meaningful gross margins.

Energy Recovery (ERII), the largest specialized energy recovery device manufacturer for SWRO, reported gross margins of 65 percent in FY2025. That number is not typical of the industrial sector it is categorized in. It reflects a product that is specified-in at the design stage, has no scheduled maintenance requirement (reducing the operator's incentive to swap it out), and generates aftermarket revenue from an installed base that grows every time a new SWRO plant comes online. Revenue in the aftermarket channel — upgrades and spare parts — grew 12 percent in 2025 and now represents 15 percent of the Water segment total.

The demand picture

Desalination growth is driven by three structural factors that are not going away:

Water stress in high-income water-scarce regions. The Middle East (Saudi Arabia, UAE, Qatar, Kuwait, Bahrain, Oman, Israel) has been the core market for decades and remains the largest single concentration of desalination capacity. These are countries with essentially no meaningful surface or groundwater resources, high per-capita water demand, and the fiscal capacity to fund infrastructure at scale. ERII's Middle East revenue was $68.2M in 2025, more than half its total.

Expansion into new geographies. India, parts of Southeast Asia, and Australia have moved from minimal desalination capacity to large-scale SWRO projects in the last decade. Water stress in coastal cities — Chennai, Perth, Singapore — is driving municipal projects that were inconceivable when SWRO costs were higher.

Energy cost declines. As renewable electricity becomes cheaper, the energy intensity argument for desalination weakens. Pairing a large SWRO plant with solar or wind generation in a sun-rich, water-scarce country like Saudi Arabia substantially reduces the lifecycle cost of water. This is an active development: NEOM and other large Saudi infrastructure projects include desalination components paired with renewable power, which would increase total SWRO capacity meaningfully over the next decade.

Project timing and the lumpiness problem

The practical challenge for investors in desalination equipment companies is that revenue does not arrive smoothly. A megaproject is a multi-year civil engineering commitment; once contracted, it generates a concentrated burst of equipment revenue during the fit-out phase. The plants then run for twenty to thirty years generating aftermarket revenue, but new project starts are geographically and politically lumpy — a drought in India triggers a burst of contracting; a budget cycle in Saudi Arabia releases a cluster of awards; a temporary slowdown in one region can make annual revenues look like demand is falling when it is really shifting in timing.

ERII's revenue fell 7 percent in 2025 — from $144.9M to $135.0M — primarily because megaproject shipments to Africa and Asia were lower. The same company's Water segment grew 20 percent year-over-year in Q1 2026 as those projects resumed. Reading annual revenue as a demand signal in this sector requires understanding the project cycle underneath it. (ERII's trailing P/E also embeds a now-wound-down CO2 segment drag, making the headline multiple a particularly poor representation of the Water business's economics — a pattern examined in Three cases where the trailing P/E ratio actively misleads.)

The niche opportunity

The sector's investment logic is clearest at the equipment layer, not the EPC layer. The pattern of recurring aftermarket revenue, switching costs embedded at the design stage, and gross margins that the competitive layers of the chain cannot approach points to the same conclusion across membranes, pumps, and energy recovery devices: the value in desalination concentrates in the components that are hardest to replace once installed.

For a sector built around solving a structural water scarcity problem that is getting more acute over time, not less, the recurring revenue from a growing installed base is the most durable part of the investment case. The lumpiness of new-plant construction is the noise; the aftermarket is the signal.