Water is essential to all life. Without water, there is no survival. From driving nutrient absorption at the microcellular level to irrigating expansive acres of cultivated farmland, water drives all human activity. From the founding of Mesopotamia on the banks of the Tigris and Euphrates to the settlements on the Yangtze that evolved into China, water has rocked the cradle of all civilization. The centrality of water in human life cannot be overstated. 

Given its importance, water has historically been used strategically as a trump card in military conquests. Around 600 BCE, the Athenian Statesman Solon reportedly poisoned the aqueduct of the Pleistrus River that supplied water to the village of Cirrha. As a result, enemy forces became severely ill and were easily defeated. Similarly, during the Siege of Uxellodunum in 51 BCE, Julius Caesar forced the surrender of the Gauls by preventing them from accessing the water supply. Such tactics were widespread across the ancient world. 

Our relationship with water is constantly evolving. With the dawn of a technological era, three major changes have occurred. First, freshwater is starting to run out, particularly in Asia, Africa, and the Middle East. While previously imperialist desires chiefly weaponized water access, current trends indicate that water wars will now be motivated by necessity. According to a United Nations Department of Economic and Social Affairs brief on water scarcity, by 2025, 1.8 billion people will experience water scarcity, and two thirds of the world will be living under water-stressed conditions. When the annual water supply per person drops below 1700 cubic meters, the region is water stressed, and if the number drops below 1000 cubic meters, a population faces scarcity. Second, while humans have always had limited ability to control water flow, such capabilities have drastically improved with modern infrastructure like dams and reservoirs. Finally, rapid scientific advances have allowed humans to exponentially increase the potency of using water as a chemical weapon. Individually, any one of these should be cause of great concern for all of humanity. All three of them in conjunction should ring the bells of catastrophe - often neglected by media in favor of more sensational headlines, water is a greater crisis in the brewing. 

Both despite and because of the growing scarcity of water, humans continue to manipulate water access for political and military purposes. The following are three contemporary structures of water weaponization. 

First, water is weaponized to attack civilians and weaken population centers. For example, between 1904 and 1908, German colonists in modern-day Namibia brutally suppressed the rebellion of the Herero people by driving them into the Namib desert and poisoning its few wells. Approximately 100,000 people were killed according to UN estimates. Recently, in 2015, the Islamic State of Iraq and Syria (ISIS) captured the Ramadi Dam in Iraq and cut off water for irrigation to the central Iraqi cities of Babil, Karbala, Najaf and Qadisiya. Although only under ISIS control for a month, this move has impacted food production in the region. In fact, ISIS has put water at the core of its expansionist strategies, according to Stratfor. Since 2013, ISIS has launched approximately 20 major (and countless smaller) attacks against Syrian and Iraqi infrastructure. According to a UN report, the group gained control of Fallujah's Nuaimiyah Dam in 2014 and subsequently flooded 10,000 houses and 200 square kilometers of fertile farmland, destroying the entire harvest. Livestock were killed, as many as 60,000 residents lost their livelihoods, and the entire city of Abu Ghraib was flooded under four meters of water. Additionally, the diversion of water left millions of people without water in the cities of Karbala, Najaf and Babil. Though these civilian attacks may initially seem to create pointless instability, ISIS has used them to achieve two strategic objectives: disrupting government troop movements and incentivizing people to join through the fact that they direct water to allied towns.

The second way in which water is exploited is by using it as a potentially untraceable weapon of mass destruction and genocide. The World Health Organisation defines chemical weapons as any toxic chemical used together with a suitable delivery method to inflict harm. A study published in the Environmental Health Perspectives journal studied the ramifications of water supply contamination by 18 replicating agents and 9 biotoxins known or likely to be weaponized, and reported concerning findings. For example, Tetrodotoxin can cause death within 6 hours due to respiratory failure. A lethal dose is conservatively estimated at 0.1 micrograms per liter of water, assuming a daily water consumption of 15 liters. This shows how easily anyone with knowledge and access can weaponize water supply. This threat has already manifested several times. In 2009, the Taliban claimed in a letter to Pakistani authorities that they had 200 liters of poisonous chemicals, including cyanide, which they would release into civilian water supplies if the then-ongoing military offensive against them was not stopped. While this particular threat was revealed to be a bluff, similar threats loom. In 1970, the Weather Underground Organization, a political group opposing the American invasion of Vietnam, attempted to obtain biological weapons to contaminate the water supplies of major US cities. Similarly, in 2003, Iraqi agents planned to poison the water supply of US troops at a military base near Zarqa; they were foiled by Jordanian authorities. 

Another cause for concern is that water can be weaponized not just by governments and large non-state actors, but also by any individual with adequate knowledge of chemistry. For example, in 2003, 64 people were hospitalized in the Henan Province of China because a man who wanted to boost his water purifier sales poisoned a local reservoir. 

Finally, as water begins to run out in Asia, Africa, and the Middle East, water access will not only be weaponized, but will drive wars. CNA predicts these conflicts will fall into  four main categories: civil unrest and riots stemming from civilian frustration; localized regional, ethnic, or communal violence; increased terrorism and potentially civil war; and state-versus-state conflict via both political and conventional warfare.

Signs of potential state on state conflict have already manifested between India and Pakistan near the Indus Basin, where there will be moderate risk of drought and decreased food security by 2040, according to the Department of State Global Water Security report. The 1960 Indus Water Treaty (IWT) - which has survived three wars - governs the water distribution of the six major Indus Basin rivers between Pakistan and India. It gives Pakistan the rights to the waters of the Indus, Jhelum, and Chenab, and India control over the Ravi, Beas, and Sutlej rivers. According to news reports, India has been considering withdrawing from the treaty since 2016 - a move Pakistan has warned will be considered a declaration of war. However, experts predict that India still does not have the adequate infrastructure to control and divert the flow of water, and it will take almost a decade for New Delhi to reach such capabilities. Thus, over the coming decade, as infrastructure projects along the Indian side of the Indus Basin are completed, India will gain an incredible amount of control over the water and, by proxy, the 144 million people in Pakistan that depend on it. Climate change will make water increasingly scarce, and India’s disdain for the IWT indicates that, without a significant decrease in tensions, the subcontinent is spiraling towards a water war. 

All of us need water equally. None of us can survive without it. If current trends continue, we are headed in a dangerous direction. Moving forward, international law, bilateral treaties and regulatory enforcements are vague and highly political. They need to be radically revised before they can be considered sufficient to provide basic levels of security to vulnerable populations. Meanwhile, on an individual level, all of us have a duty: we must conserve and use water responsibly!