On 8 September 2026, Israeli news outlet Ynet reported that a rare algae bloom along Israel's Mediterranean coast forced the temporary shutdown of five of the country's six major seawater desalination plants, cutting output at facilities that supply most of the nation's drinking water Middle East Eye. The report pointed to untreated sewage discharging from Gaza's war-damaged wastewater network as a likely contributing nutrient source thecradle.co.
Key takeaways
- Five of Israel's six major coastal desalination plants — Ashkelon, Ashdod, Palmachim, Sorek A and Sorek B — were temporarily shut down Middle East Eye.
- Desalination supplies at least 65 percent of Israel's drinking water, with most plants sited on the Mediterranean coast Middle East Eye.
- Some 40,000 cubic metres per day of untreated wastewater from Gaza's destroyed sewage system is reportedly flowing into the sea thecradle.co.
- The bloom organism has been identified as a cyanobacterium of the genus Synechococcus, with the exact species and trigger still under investigation Middle East Eye.
- Israel's water authority said supplies were stabilised by drawing on the Sea of Galilee, groundwater wells and reservoirs, with some agricultural and public irrigation restricted Middle East Eye.
What happened
The bloom spread along Israel's Mediterranean coast, disrupting seawater desalination plants that provide much of the country's drinking water, CNN reported, citing Mekorot, Israel's national water company Middle East Eye. "An event of this kind has never occurred before in Israel … it was an extremely rare event," said Lior Gutman, a spokesperson for Mekorot Middle East Eye.
Avner Gross, head of Ben-Gurion University's Climate Change Laboratory, told Ynet that satellite imagery showed similar algae-filled waters around Egypt's Nile Delta, where agricultural runoff enters the Mediterranean, and that a pollution source in the southern Gaza Strip was the most plausible explanation for the Israeli event Middle East Eye. Gross wrote on X that global warming had turned the Mediterranean into "a bathtub in August," adding, "Add phosphorus and nitrogen pollution and you get a deadly algal bloom. Coincidentally, in recent days there were weak, steady winds that mixed the fertiliser from the sewage along Israel's coast. A perfect storm." thecradle.co.
Other researchers urged caution. Noga Armi, chief executive of Israeli environmental organisation Zalul, said untreated sewage from Gaza was a contributing factor, while Tamar Guy-Haim, a marine ecologist at Israel's National Institute of Oceanography, said the probability that Gaza sewage was the main driver of the bloom was relatively low Middle East Eye. Or Bialik, a researcher at Israel Oceanographic and Limnological Research, told Haaretz: "I've worked in the Mediterranean Sea for a long time and have never seen anything like this. The water is green like a lake. The turbidity is such that you can't see your instruments after half a metre" Middle East Eye.
Scientists told CNN and Haaretz that the bloom likely began near Egypt's Nile Delta and drifted north with ocean currents, and that warming Mediterranean waters, strong sunlight, currents and a recent storm that increased turbidity were also in play Middle East Eye. Edo Bar-Zeev, a water researcher at Ben-Gurion University, told CNN the event should not be treated as a one-off. "It's a fair estimation that this will not be a once-in-a-lifetime kind of event … you can assume that this will occur more and more through climate change," he said thecradle.co. Researchers had not, as of the report date, identified a definitive cause Middle East Eye.
Specification read
The reported nutrient load is 40,000 cubic metres of untreated wastewater per day reaching the Mediterranean, equivalent to 40 MLD of raw sewage bypassing any treatment train and feeding the coastal water body that Israel's seawater reverse-osmosis plants draw from thecradle.co. A conventional municipal or coastal-city plant of that throughput is normally specified with screening, grit removal, primary clarification, biological treatment (A2O or MBR for nutrient removal), tertiary polishing and disinfection before reuse or discharge Integrated Sewage Treatment. The failure mode here sits upstream of the desalination intake: nutrient overload (phosphorus and nitrogen) and a warm, stratified, turbid water column allowed a Synechococcus cyanobacterial bloom to form, and once biomass reached the intake screens, operators had no option but to stop production Middle East Eye. If your plant is a coastal SWRO facility drawing from a eutrophication-prone sea at flows of tens of MLD with BOD in the influent shoreline waters in the tens of mg/L, a single bloom event of this scale can take a majority of national capacity offline at once, and the mitigation is upstream — better regional sewage treatment and intake-side barriers Water Purification. Buyers comparing RO pretreatment trains for high-turbidity, high-organics seawater should expect to revisit cartridge filtration, DAF and ultrafiltration stages whenever a utility reports sustained chlorophyll-a or cyanobacteria events Municipal.
FAQ
How long did the desalination shutdowns last? The reports describe the five plant shutdowns as temporary, with Israel's water authority stabilising supply by drawing on the Sea of Galilee, groundwater wells and reservoirs while restricting some agricultural and public irrigation Middle East Eye. No restart date was given in the sources.
Which plants were taken offline? Ashkelon, Ashdod, Palmachim, Sorek A and Sorek B — five of Israel's six major Mediterranean desalination units Middle East Eye.
What is the cost impact on a buyer procuring pretreatment for a similar seawater RO plant? Reported contract values or unit costs were not provided in the sources. Capital and OPEX for enhanced seawater pretreatment (DAF, UF, cartridge filtration) typically rise materially when algae/cyanobacteria events are added to the design basis (general industry range, not from the sources).
What is the expected lead time if a Mediterranean utility now has to add or upgrade pretreatment? No project schedule was reported. Containerised DAF and UF skids are commonly delivered in weeks to a few months for retrofit, while full civil builds run longer (general industry range, not from the sources). For parallel reading on RO versus ion-exchange choices for high-strength reuse streams, see RO vs Ion Exchange for API and Formulation Wastewater: 2026 OPEX Verdict for Cooling Blowdown Reuse and RO vs Ion Exchange for F&B Process Wastewater: 2026 OPEX Comparison.
