It’s raining PFAS: As the Middle East welcomes winter rains, scientists warn rainwater is no longer safe to drink
After months of scorching summer heat, the first winter rains are approaching the Middle East. In Israel, Lebanon, Jordan and Syria, rain means relief: cooler temperatures, greener hillsides, replenished reservoirs and the promise of another growing season. Local prayers call for dew in the summer but rain the winter. Rain is a blessing, but now with the plastics and forever chemicals pumped into our land, air and waters rainwater is no longer safe to drink.
In a new to me study (it was published in 2022), scientists from Stockholm and Zurich have found that rainwater around the world contains persistent industrial chemicals known as PFAS, or “forever chemicals,” sometimes at concentrations exceeding drinking-water safety guidelines. This is meaningful because the Swiss collect rainwater from roofs to water their gardens. Rain goes into our backyards, it funnels into rivers, it flows to the sea. Seems like we are plugged into a perpetual loop of chemical warfare falling from the sky.
The researchers concluded that PFAS contamination has spread so extensively through the atmosphere that even rainwater collected in some of the most remote places on Earth, including Antarctica and the Tibetan Plateau, exceeds certain health-based guidelines of PFAS to consume.
For a water-stressed region like the Middle East, where every drop of winter rainfall matters, the findings raise uncomfortable questions about what we consider clean water.
“There has been an astounding decline in guideline values for PFAS in drinking water in the last 20 years,” said Ian Cousins, lead author of the study and professor at Stockholm University’s Department of Environmental Science. “Based on the latest U.S. guidelines for PFOA in drinking water, rainwater everywhere would be judged unsafe to drink,” he said, referring to the guidelines available when the study was published in 2022.
“Although in the industrial world we don’t often drink rainwater, many people around the world expect it to be safe to drink and it supplies many of our drinking water sources.”
PFAS, short for per- and polyfluoroalkyl substances, are a large family of synthetic chemicals used in products including waterproof clothing, nonstick cookware, stain-resistant textiles, food packaging and certain firefighting foams. The chemicals made headlines recently when PFAS were found in Lululemon yoga pants. Companies process them and dump them with no environmental cares. See the Dupont case. We’ve also reported on how Germany is tracking PFAS‘s in drinking water.
Their chemical stability makes them useful to manufacturers but problematic for the environment. Many PFAS break down extremely slowly, while others transform into similarly persistent substances. Certain well-studied PFAS have been associated with increased cholesterol, impaired immune responses, reproductive and developmental problems, and some cancers. Scientists urge that more research is needed.
Over the past two decades, scientists have learned more about their health risks, prompting regulators to dramatically lower recommended exposure limits for certain chemicals. Cousins noted that the U.S. drinking-water guideline for PFOA, one of the best-known PFAS chemicals, had fallen by a factor of 37.5 million over the preceding two decades.
The problem is not necessarily that rainwater has suddenly become more polluted. It is that researchers now understand how potentially harmful even very low concentrations of certain PFAS can be.
How did industrial chemicals reach the world’s rain?
PFAS travel through waterways, soils and the atmosphere, moving far beyond the factories and consumer products from which they originated. Scientists at Stockholm University have spent years investigating how these chemicals move through the air. One surprising discovery is that oceans, once thought to be a final destination for some PFAS pollution, can send these substances back into the atmosphere.
As waves break, tiny sea spray aerosols can carry PFAS from seawater into the air. These particles can then travel with atmospheric currents before returning to Earth through rain and snow. In other words, chemicals discharged into the environment decades ago can continue circulating around the planet possibly forever.
“The extreme persistence and continual global cycling of certain PFAS will lead to the continued exceedance of the above-mentioned guidelines,” said Professor Martin Scheringer, a co-author of the study affiliated with ETH Zurich and Masary University. The researchers argue that PFAS pollution has crossed a planetary boundary, a threshold beyond which human activity risks destabilizing the Earth’s environmental systems.
What does this mean for the Middle East?
The Mediterranean rainy season is beginning, and its arrival is especially important in a region already facing chronic water shortages, drought and climate change.
Israel relies heavily on desalination for its municipal drinking water, but winter rainfall still replenishes groundwater, streams, agricultural soils and the Sea of Galilee. Also the desalination membranes got clogged this year after an algal bloom forcing a couple of plants to go offline. Elsewhere in the Middle East, rainwater harvesting and seasonal rainfall remain essential to rural communities and agriculture.
Between August 29 and early September 2026, five of Israel’s six major Mediterranean desalination plants were temporarily shut down after a massive bloom of microscopic algae caused unusually high turbidity in seawater, disrupting the plants’ filtration systems. The affected facilities were Ashkelon, Ashdod, Palmachim, Sorek A and Sorek B; only Hadera continued operating normally.
Scientists from Israel Oceanographic and Limnological Research traced the bloom primarily to Egypt’s Nile Delta, with currents carrying the microorganisms northward along the Mediterranean coastline. Researchers subsequently identified cyanobacteria of the genus Synechococcus.
However, environmental experts also raised concerns that untreated sewage flowing into the Mediterranean from Gaza, where wastewater infrastructure has been severely damaged during the war, may have supplied nutrients that intensified the bloom. The Israeli environmental organization Zalul argued that sewage from Gaza contributed to the crisis, although marine scientists disagreed about its significance and a direct causal link was not established.
By September 9, all five facilities had resumed at least partial operations, but reduced production and restrictions on agricultural irrigation continued; desalination capacity was still recovering later that month.
“Due to the global spread of PFAS, environmental media everywhere will exceed environmental quality guidelines designed to protect human health,” said Scheringer, explaining the study’s conclusions on PFAS.
There is also a question of accountability. Dr. Jane Muncke, managing director of the Food Packaging Forum Foundation in Zurich, who was not involved in the research, argued that the financial burden of removing PFAS from drinking water should fall on the industries responsible for producing and using them. How can polluters who don’t want to pay for their pollution be forced to pay?
