Five of Israel's six coastal desalination plants shut down on Sunday after a miles-long microalgae bloom swept the Mediterranean, knocking out the source of most of the country's drinking water, according to Mekorot, the national water company CNN reported on 4 September 2026. By Thursday only one of the affected plants was running at full capacity CNN said.
Key takeaways
- Five of six Israeli coastal desalination plants shut on Sunday after a microalgae bloom, per Mekorot CNN.
- Desalination supplies at least 65% of Israel's drinking water, most of it from the Mediterranean coast CNN.
- The bloom stretched more than a dozen miles and is believed to have originated in the Nile Delta Межа. Новини України..
- Sea temperatures reached 30 degrees Celsius amid a storm that raised turbidity, Mekorot said CNN.
- Mekorot pumped water from the Sea of Galilee, activated wells and used national reserves to cover the gap Межа. Новини України..
What happened
Mekorot told CNN that the affected plants began shutting on Sunday, with privately operated facilities partially restarting through the week. By Thursday only one was at full capacity, and in roughly 99% of cases there was no drinking water shortage, spokesperson Lior Gutman said CNN reported. "An event of this kind has never occurred before in Israel … it was an extremely rare event," Gutman told the outlet.
Edo Bar-Zeev, an associate professor in water research at Ben-Gurion University, said the bloom was a "sporadic, vast event of contaminates" along the coastline, stretching more than a dozen miles at least CNN. He added that the bloom is believed to have originated in the Nile Delta and travelled north with the sea's currents Межа. Новини України.. "This is the first time I have seen a phenomenon on this scale," Bar-Zeev said in the Межа. Новини України. report.
Most Israeli plants run reverse osmosis, with pretreatment ahead of the membranes CNN. The bloom fouled those membranes: microalgae and the substances they produce can damage them, and high suspended solids overload the pretreatment step Межа. Новини України.. Mekorot cited a "very unusual combination of factors," including a sea storm that lifted turbidity and pushed sea temperatures to 86 Fahrenheit (30 degrees Celsius) and above CNN.
To keep supplies flowing, the national grid drew on the Sea of Galilee, switched on groundwater wells and drew down reserves CNN. Some cities imposed short-term local restrictions on garden irrigation and pool filling; the heaviest impact fell on farmers who irrigate with drinking-quality water rather than recycled water, Gutman said CNN reported. The shutdown landed in summer, when Israeli water demand is at its highest Межа. Новини України..
Michael Christopher Low, director of the Middle East Center at the University of Utah, told CNN that the episode exposes the risk of centralised desalination: "This event is causing considerable alarm and even some criticism that the system is too vulnerable to a dramatic disruption." The Межа. Новини України. report added that Bar-Zeev warned an oil spill near a plant would keep it offline far longer than this bloom did.
Specification read
Putting the reported scale into buyer units, the headline figure is qualitative rather than volumetric: sources describe five of six coastal plants offline, with only one at full capacity by Thursday CNN. The sources do not give a combined flow in million litres per day or cubic metres per day, so a class range is offered here: a Mediterranean coastal reverse-osmosis seawater plant serving a national grid typically runs in the range of 100,000–600,000 m³/day per site (general industry range, not from the sources). For a Mediterranean RO train, the relevant unit operations are intake screening and chlorination, dual-media or membrane filtration pretreatment, cartridge filtration, then the RO membranes themselves, with energy recovery and brine discharge. The failure here sits in the pretreatment stage, where high turbidity and algal organic matter overload the filters and foul the membranes CNN.
For procurement: if your plant is a large coastal or estuarine desalination facility in the 100,000–600,000 m³/day band, with high pretreatment loading, summer-peak demand and growing regulatory pressure around discharge and reuse, this incident maps directly onto your intake and pretreatment design. It is a reuse and pretreatment failure case as much as a feedwater event: turbidity, algal organic matter and biomass are exactly the parameters that decide whether the membranes stay online. Buyers scoping similar builds should look at pretreatment upgrades, dissolved-air flotation or ceramic-membrane pretreatment ahead of RO, and at buffer storage that lets a plant ride out a multi-day feedwater excursion. Pages worth a look while specifying: Water Purification for RO pretreatment options, Industries We Serve for adjacent municipal and industrial references, and a related read on MVR Evaporator Maintenance Guide 2026: Procedures, Schedules and Cost Control. For a comparable pretreatment case study, see Data Center Cooling Blowdown Treatment in Jeddah 2026: Process Specs, Cost & Compliance, and the Municipal page for full municipal treatment trains.
FAQ
What caused the Israeli desalination shutdowns? A microalgae bloom more than a dozen miles long in the Mediterranean, believed to have come from the Nile Delta, fouled reverse-osmosis pretreatment and membranes CNN.
How many plants were affected and for how long? Five of six coastal plants shut on Sunday; by Thursday only one was at full capacity, with others partially restarted CNN. Sources do not give a firm date for full reinstatement.
What is the lead time and cost class for a pretreatment upgrade that handles algal blooms? Lead times for an RO pretreatment retrofit at this scale typically run 9–18 months from order to commissioning, with capital cost in the low tens of millions of US dollars per site (general industry range, not from the sources); supplier selection should weigh DAF, ceramic UF and conventional dual-media options against local discharge limits.
How exposed is a typical coastal RO plant to a similar event? Any seawater RO plant that draws from a warm, nutrient-influenced coast and lacks robust intake screens, DAF or ceramic-membrane pretreatment is structurally exposed to the same kind of multi-day shutdown Межа. Новини України..
