Water Supply: Counter-Terrorism

Water Supply: Counter-Terrorism


The water supply in many communities in the developed world comes from a surface water source such as a lake. Water can also be pumped from aquifer located underground. Typically, the water is routed to a treatment plant, where a variety of physical and chemical processes render the water safe to drink. The "finished" water is then pumped through pipes (i.e., the distribution system) to the consumer's taps.

For over a century this process has been geared toward providing high quality water, without consideration of the security of the acquisition, treatment, and distribution of water. However, particularly since the 1990s, the threat of a deliberate contamination of water supplies has become more probable.

In the wake of the September 11, 2001 terrorist attacks on the World Trade Center and the Pentagon in the United States, surface water supplies, water treatment plants, and distribution systems were quickly recognized as potential targets of a terrorist attack. While water facilities are often equipped to discourage mischief (i.e., a chain link fence surrounding a reservoir), virtually no water facilities are designed to prevent a deliberate and coordinated attack.

Many compounds dissolve in water and microorganisms are so small that, for example, up to 6 million bacteria need to be present in each milliliter of water before the water will appear less than crystal clear. Thus, the addition of a lethal quantity of a potent poison or disease-causing microorganism to a water supply could be done without attracting undue notice.

During the 1990s, and especially since the events of September 11, 2001, efforts to develop effective strategies to counter a terrorist attack on water supplies have been widely debated.

The fact that major urban systems need to supply huge quantities of drinking water every day could already be a counter-terrorist strategy. Even given the ease by which a reservoir could be contaminated, the large volume of the water reservoirs of major urban centers would dilute the added poison to very low levels. A lethal dose of a poison at the consumer's tap would require the addition of a huge amount of the contaminant. For example, it has been estimated over 400,000 metric tons of hydrogen cyanide would have to be added to the Crystal Springs Reservoir—a major reservoir for the city of San Francisco—to supply enough poison to kill or debilitate someone drinking one glass of water from the reservoir.

However, smaller reservoirs are at risk, as are smaller water tanks. Increased security at treatment plants would be an effective deterrent to sabotage. However, such security would be expensive and the cost would be passed to the consumer.

In most municipalities, water treatment involves the addition of chlorine or chlorine products to kill microorganisms. The deliberate disabling of the chlorination system of a treatment plant would make contamination of the drinking water a certainty. For example, a breakdown in the chlorination of the drinking water of Walkerton, Ontario, coincident with the run-off from a cattle field that contaminated the water supply with Escherichia coli O157:H7 , sickened over 2,000 people and killed at seven people in the summer of 2000.

Even a secure treatment facility supplying chlorinated water is no guarantee of safe water. Recent history has shown that chlorinated water is susceptible to contamination by microorganisms that are resistant to the chemical. Specifically, the protozoa called Giardia and Cryptosporidium have a spore-like stage in their life cycles that survives exposure to chlorine. A Cryptosporidium contamination of the water supply of Milwaukee, Wisconsin, sickened over 200,000 people and killed almost 100 people.

While illness outbreaks with the protozoa have so far been accidental, the use of the microorganisms as a weapon is conceivable. In the United States, municipalities have been legislated to provide alternate means of dealing with drinking water to counter the threat posed by Giardia and Cryptosporidium . This legislation has been prompted by health concerns. Nonetheless, it will prove to be a counterterrorism measure.

The distribution system that carries water from the treatment plant to the consumer's taps is another potential target of terrorism. The high pressure inside the pipes would make the introduction of a contaminant difficult. However, the lack of security along the distribution system could enable a dedicated group to commission the digging equipment needed to uncover a pipe and stop water flow long enough to contaminate the water.

Patrolling a distribution system is impossible. For now, the most effective counter-terrorism strategy is to make manholes and storage tanks inaccessible.

Another microbial terrorist threat to drinking water is Bacillus anthracis . This bacterium, which is the cause of anthrax, can form a very hardy structure known as a spore. Studies have determined that the spore form can survive in chlorinated water for at least two years. If ingested in a glass of drinking water, or inhaled in the humid environment of a shower or bath, the spores can revive, and the growing bacteria can cause the disease.

Other chlorine-resistant microorganisms that have been identified as bioterrorism agents include Clostridium perfringens , Yersinia pestis (the cause of plague), and biotoxins (e.g., aflatoxin and ricin).

Countering the deliberate use of such microorganisms will necessitate the rapid detection of even tiny quantities of the microorganisms or their toxic products. Use of rapid detection devices in an early warning system would be an effective counter-terrorism strategy, albeit one that would require dedicated personnel or hardware to monitor the water system.

One promising technology is the use of an electronic sensor ("the electronic nose") to detect chemicals. This method has been successful in detecting spoilage and disease causing bacteria present on fruit by virtue of the unique chemical compounds given off by the bacteria. However, the electronic nose would have to be adapted for use with water.

A detection method that already successfully detects and identifies bacteria such as Escherichia coli in fresh water relies on the binding of fluorescent antibodies to the surface of the bacteria and the detection of the bound antibodies by the resulting fluorescence. A prototype of the device is portable and so can be taken to hydrants for the testing of water throughout a distribution system. When in production within the next several years, the device will offer a means of rapidly monitoring water for contaminants.

Another promising technology relies on the recovery of genetic material (deoxyribonucleic acid; DNA) from the sample, and the detection of sequences of the DNA that are unique to the target bacteria by the use of a mirror image piece of DNA that will selectively bind to the target sequence. DNA microchips utilize this technique to detect bacteria from samples as complex as soil and ocean water.

Thus, there is potential for the development of rapid tests to detect bacterial contamination of drinking water. Whether the benefits of implementing an early warning system of chemical and microorganism detection will justify the costs remain to be determined.

In the short term, the best counter-terrorism strategy for many water systems will continue to involve a survey of the system in order to identify points where the system is vulnerable (i.e., unlocked hydrants) and taking action to secure those points (i.e., locking hydrants). As well, public notification of water contamination, and response of authorities (e.g., police, fire department, and medical personnel) to a contamination should be an integral part of a community's emergency response plan.

Despite the vulnerability of water to deliberate contamination, the reality continues to be that the probability of such action is very low. A terrorist can deliver a lethal payload by air or through routes like the postal system more easily and using less microorganisms than would be required for the contamination of a water supply.



Lesser, Ian O., and Bruce Hoffman. Countering the New Terrorism. Santa Monica: Rand Publications, 1999.


Betts, K. S. "DNA chip technology could Revolutionize Water Testing." Environmental Science and Technology no. 33 (1999): 300A–301A.

Burrows, W. D., and S. E. Renner. "Biological Warfare Agents as Threats to Potable Water." Environmental Health Perspectives no. 107 (1999): 975–84.

Foran, J. A., and T. M. Brosnan. "Early Warning Systems for Hazardous Biological Agents in Potable Water." Environmental Health Perspectives no. 108 (2000): 993–96.

Weckerle, J. F. "Domestic preparedness for events involving weapons of mass destruction." Journal of the American Medical Association no. 283 (1997): 435–38.


Biological Warfare
Chemical Warfare
Pathogen Transmission
United States, Counter-terrorism Policy

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