Gulf states, being most water-scarce in the world, many Middle Eastern countries resort to desalination for their clean water needs. But Gulf states are heading for ?peak salt?, a vicious cycle in which the more they desalinate, the more concentrated wastewater, brine, is pumped back into the sea and as the water becomes saltier, desalination becomes more expensive.

The Middle East is home to 70% of the world?s desalination plants – mostly in Saudi Arabia, the United Arab Emirates, Kuwait, and Bahrain. The process is cost and energy intensive it pumps seawater through special filters or boils it to remove the salts. The resulting waste water is pumped back into the sea converting the 250,000 sq km Gulf into the sea, which is shallow, just 35 metres deep on average and enclosed. The water in the Gulf is 25% saltier than normal seawater. Peak salt is the point at which desalination becomes unfeasible.

With groundwater sources either exhausted or non-existent and climate change bringing higher temperatures and less rainfall, Gulf states plan to nearly double the amount of desalination by 2030. This is bad news for marine life and for the cost of producing drinking water – unless something can be done about the brine. It also contains high concentration of metal.  This water cannot be used in agriculture and city, so mostly they throw it away to the sea. As a result, it damages ecology of the sea. Polluted water affects sea creatures it damages biodiversity of Red Sea, Gulf of Aden, and Arabian Sea.

The effluent from desalination plants is a multi-component waste, with multiple effects on water, sediment and marine organisms. Salinity, temperature and density are elevated. With increasing temperature and salinity, oxygen becomes less soluble in seawater. The lack of dissolved oxygen could be toxic to marine organisms. Another major pollutant of distillation processes is chlorine, which is added to the desalination plant feed water to prevent bio-fouling on heat exchanger surfaces. Chlorine is a strong oxidant and highly effective biocide. Residual levels in the discharge may therefore be toxic to marine life in the discharge site. The use of chlorine also leads to the formation of oxidation by-products such as halogenated organics. These compounds are often carcinogenic to animals. The waste brine often contains low amounts of heavy metals that pass into solution when the plant's interior surfaces corrode. Many benthic invertebrates feed on this suspended or deposited material, with the risk that metals are enriched in their bodies and passed on to higher trophic levels. Other chemicals like anti-scalants are commonly added to the feed water in both distillation and RO plants to prevent scale formation on heat exchanger surfaces, inside tubes, or on RO membranes which impair plant performance.

Climate change policymakers in the region are pushing for water pricing and awareness campaigns around consumption to explain to governments and citizens that they can?t continue to use water in the same way.