1948 "Cast thy bread" biological warfare campaign by Israel

Operation "Cast Thy Bread" (Hebrew: Shallah Lahmekha) was a top-secret biological warfare campaign conducted by the Haganah and the Israel Defense Forces (IDF) during the 1948 Arab-Israeli War. Officially confirmed by historians Benny Morris and Benjamin Kedar in a 2022 landmark study, the operation utilized typhoid bacteria to contaminate drinking water wells in Palestinian villages. 

Strategic Objectives

The campaign, which began in April 1948, aimed to achieve three primary military goals: 

• Prevent Return: To discourage and prevent displaced Palestinian Arab villagers from returning to homes captured by Jewish forces.
• Hinder Arab Armies: To disrupt the logistical capabilities and advancement of invading armies from neighboring Arab states.
• Scorched Earth: To compromise water supplies in Jewish settlements that faced imminent capture or evacuation, ensuring no usable water remained for advancing Arab troops. 

Key Figures and Leadership

The operation was not a rogue initiative but was orchestrated by the highest echelons of Israel's pre-state and early military command: 

• David Ben-Gurion: Israel's first Prime Minister, who authorized the overall program.
• Yigael Yadin: The de facto Chief of General Staff, who oversaw the military implementation.
• Yohanan Ratner: The operational commander who coordinated the campaign.
• Moshe Dayan: Served as an early field operative, acting as a smuggler to transport the biological agents from laboratory facilities to active military units. 

Documented Missions and Incidents

• Acre (Akka): The water supply was contaminated with typhoid, triggering a local epidemic that sickened dozens of local citizens and caused several fatalities. 
• Gaza Infiltration: In May 1948, two Israeli soldiers disguised as Arabs attempted to contaminate a crucial water well in Gaza to block the Egyptian army. The operatives were captured, court-martialed, and executed by Egyptian authorities. 
• Target Expansion: While initial operations targeted local Palestinian communities and the Egyptian line, the high command drafted expansion blueprints for operations into Syria, Lebanon, and Egypt, though these were never executed. 

Historical Legacy

The tactical execution of the campaign was overall amateurish and faced strong opposition from several prominent Israeli scientists and politicians. Consequently, it did not significantly alter the strategic outcome of the war. For decades, the Israeli security establishment actively classified and suppressed archival documentation regarding the operation. The structural precedents and informal research frameworks established during "Cast Thy Bread" later laid the groundwork for the formal creation of the Israel Institute for Biological Research (IIBR) in 1952. 

AI uses huge amounts of water

AI uses obscene amounts of water. When they finish is the water still suitable for the usual purposes? Is it hot enough to be a heat source? Is it clean enough to be part of municipal water supplies?

No, the water exiting AI data centers is not suitable for immediate public use, but it is highly valuable for industrial heat networks and can be recycled. 

When we talk about the "obscene amounts of water" AI uses, it is important to divide this into two categories: indirect water (used by power plants to generate the electricity the AI needs) and direct water (used on-site at the data center for cooling). 

For the water physically used on-site inside the data center, here is exactly what happens to it after it finishes cooling the AI servers: 

1. Is it hot enough to be a heat source?

Yes, it is an excellent heat source, though it often requires a minor assist. 

• The Temperature: Water used in standard data center cooling loops typically leaves the servers at temperatures between 86°F and 140°F (30°C to 60°C). Advanced direct-to-chip liquid cooling systems can push return water temperatures as high as 149°F (65°C). 
• How It Is Reused: This water is not hot enough to boil or create steam, but it is perfect for district heating networks. Cities (especially in Europe, like Helsinki) pipe this warm water directly out of data centers. Local utilities use large industrial heat pumps to bump the temperature up to roughly 176°F (80°C) to heat thousands of nearby homes, offices, and greenhouses. 

2. Is it clean enough to be part of municipal water supplies?

No, it cannot be pumped straight back into your tap, but it is not toxic. 

• The Problem (Concentration): Most data centers use evaporative cooling towers. As the water absorbs heat, a massive amount of it evaporates into the sky as pure water vapor. The water left behind becomes highly concentrated with the minerals, salts, and sediment originally found in the water. 
• The Chemicals: Operators add anti-scaling chemicals, biocides, and corrosion inhibitors to the water to protect the multi-million-dollar computing infrastructure from algae and rust. 
• The Result: This leftover wastewater—known as "cooling tower blowdown"—has extremely high Total Dissolved Solids (TDS) and an altered pH level. It must be sent to a municipal wastewater treatment plant to be cleaned before it can safely re-enter the environment or water supply. 

3. Is it still suitable for "the usual purposes"?

Only if "the usual purposes" mean heavy industrial reuse.
Because the leftover water is mineral-heavy and contains treatment chemicals, you cannot use it for drinking, bathing, or agricultural irrigation. However, it is perfectly suited for industrial purposes. 

Data centers are increasingly deploying on-site filtration systems to clean and recycle this blowdown water, running the exact same water through the cooling loops up to 4 to 5 times before finally discharging it. Furthermore, many modern AI facilities are switching to closed-loop systems. In a closed loop, the water is sealed inside pipes, acts simply as a vehicle to move heat, never evaporates, and is used infinitely without requiring a constant stream of fresh municipal water.