Brine: desalination's second product

The global census is blunt. Some 15,906 desalination plants make about 95 million cubic metres of water a day and 141.5 million cubic metres of brine. The Middle East and North Africa produce 48% of the water but 70.3% of the brine.¹ Discharge to the sea is by far the cheapest disposal route.¹ The questions now are how well it is regulated, and whether any of it can be sold.

Why the Gulf makes so much of it

The ratio depends on the technology. Seawater reverse osmosis recovers about 42% of its intake as fresh water, multi-stage flash 22% and multi-effect distillation 25%.¹ The Gulf built its fleet on thermal plants, so the region runs at an average recovery of about 0.25. That means roughly two cubic metres of brine for every one of water. Saudi Arabia, the UAE, Kuwait and Qatar make 32% of the world’s desalinated water and 55% of its brine.¹

That ratio falls as the fleet converts. On the same recovery figures, replacing a flash plant with reverse osmosis cuts brine per cubic metre of water by about 60%. The brine that remains is more concentrated but cooler. The Aqaba carrier’s reject will run 1.7 to 1.8 times ambient salinity, only 0.5 to 1°C warmer, with no copper or antifoams of the kind thermal plants discharge.⁵

The basin and the outfall

The basin-scale evidence is reassuring. Desalination output equals about 2% of the Gulf’s net yearly evaporation, projected to reach 8% by 2050. A strong overturning circulation flushes dense water out through the Strait of Hormuz. Even in worst-case scenarios basin-wide salinity is unlikely to rise by more than 1 psu, and it will probably stay well below 0.5.²

The same authors are explicit that this says nothing about the water around an outfall. Hot, hypersaline, chemically dosed and hypoxic brine has direct local effects on marine life, a question they set aside.² Dense brine can also form underflows along the seabed that strip oxygen from the receiving water.¹ That is where regulation actually bites.

What the rules say

Lender standards are clearer than most national ones. The IFC’s water guideline describes brine constituents but sets no numeric salinity limit, while its general wastewater guideline caps warming at 3°C at the edge of a mixing zone.³ The Aqaba to Amman carrier adopted a tighter project standard. Salinity may be no more than 2% above ambient 100 metres from the diffusers, on about 400 million cubic metres of brine a year.⁴ Its consultants added end-of-pipe limits for oxygen, iron, chlorine and pH, relocation of corals in the pipeline path, and seasonal mapping of the plume.⁵

National rules are uneven. Oman’s 2005 decision limits salinity change to 2 parts per thousand and warming to 1°C within a circle 300 metres across around any marine discharge.⁶ Saudi regulations define desalination brine as wastewater and require monitoring programmes at desalination plants.⁷ Abu Dhabi’s marine discharge specification, by contrast, exempts reject brine from desalination and power plants altogether.⁸

From disposal cost to product

Brine is a dilute ore, and the arithmetic is the obstacle. The Saudi Water Authority’s own report estimates that the entire global market for minerals from the main seawater ions could be met from about 10% of the world’s brine. It also concludes that brine mining is not a viable route to zero liquid discharge, because the volumes are too large.⁹ Jones and colleagues name the barrier as the cost and energy demand of treatment and recovery.¹

The real pipeline is short. The authority runs a nanofiltration plant at Shoaibah that extracts magnesium-rich brine and adds it back to drinking water. It is building a demonstration plant at Haql designed for 2,000 tonnes of salt and 2 tonnes of bromine a year.⁹ Two larger plants at Ras Al Khair, announced with Chinese partners in January 2024, targeted operation in the first quarter of 2026.¹⁰ Independent confirmation of commissioning had not appeared by April 2026.¹¹

NEOM’s plan went further, and then stopped. A zero-liquid-discharge desalination project at Oxagon, meant to supply industry with salt, bromine, magnesium and other products, was discontinued in May 2024 when its development agreement expired.¹² NEOM then sought proposals for a conventional reverse-osmosis plant without brine mining.¹¹

In the region

Brine is now a line in every large regional appraisal. The Aqaba to Amman carrier sets the disclosure standard: its marine works sit about 3 km south of the protected Aqaba Marine Reserve and 1.5 km from Saudi waters, and its assessment must model discharges across the border.⁴⁵ Kuwait has bench-scale tests on rejected brine from two plants. The review that reports them concludes that at present commodity prices, energy and material costs frequently exceed mineral revenue.¹³ Gulf purchase agreements still price only the water, as the tariff benchmarks show.

The case study

One scheme in this sector, examined in full: what was built, what it cost, what worked and what did not.

Who is doing this

The buyers and operators behind the procurements this brief describes.

• Saudi Water Authority (SWA)Regulator · Saudi Arabia
• Ministry of Water & Irrigation (MWI)Ministry · Jordan
• Emirates Water & Electricity Company (EWEC)PPP procurer · United Arab Emirates
• VeoliaDeveloper / operator · Regional

Mandates, procurement routes and the rest of the region’s institutions are in the decision-maker directory.

What to watch

• 2026Commissioning of the two Ras Al Khair brine-mining plants, targeted for the first quarter of 2026 and still unconfirmed in April.¹⁰¹¹ It is the only programme in the region with industrial-scale construction reported.
• PendingThe updated environmental assessment for the Aqaba to Amman carrier, which must add non-routine discharges and transboundary impacts to the 2022 brine model.⁴

Further reading

• Jones, E. et al. (2019), “The state of desalination and brine production: a global outlook”, Science of the Total Environment 657. The census every brine figure here starts from. doi.org
• Paparella, F. et al. (2022), “Long-term, basin-scale salinity impacts from desalination in the Arabian/Persian Gulf”, Scientific Reports. Why the Gulf itself is not getting saltier, and what the model leaves out. pmc.ncbi.nlm.nih.gov
• Saudi Water Authority, Seawater desalination brine mining. The most candid operator account of what brine can and cannot yield. swa-cdn.swa.gov.sa
• IFC, environmental and social review summary for the Aqaba to Amman carrier (2025). The fullest public brine disclosure on any regional project. disclosures.ifc.org
• Smart Water Magazine, “Brine’s second act: mineral extraction as revenue stream?” (May 2026). A sober survey of where brine mining actually stands. smartwatermagazine.com