Drinking Water Systems: Vulnerability Assessments and the Use of Chlorine

David B. Fischer, M.P.H., J.D.
Jessica Stuart, J.D.

The terrorist acts of Sept. 11, 2001 have brought increased resolve to safeguard our nation's drinking water supplies. Even in the best of times, this is a daunting task. There are literally tens of thousands of drinking water systems that service rural and urban communities throughout the United States. Although the sheer number of systems might frustrate attempts to uncover generalities, one generality clearly stands out B the use of chlorine as a disinfectant. Some form of chlorine is used in 98% of U.S. drinking water systems that disinfect. In fact, chlorination of drinking water is widely viewed as one of the most significant public health successes of the modern age.

Chlorine is used not only to disinfect the water before it leaves the plant, but also to maintain a protective disinfectant residual throughout the water system and ultimately to the tap. Chlorine as a disinfectant can be used in the form of compressed gas, sodium hypochlorite (liquid bleach), or calcium hypochlorite, as a granual solid or compressed tablets. By far, the most widely used form of chlorine is chlorine gas. It is generally stored in 150 b cylinders, 1 ton cylinders, or 90 ton rail cars, depending on the size of the water system.

Chlorine gas in particular is widely used for drinking water disinfection because it is effective, relatively easy to use, cost-effective and has an excellent safety record. But like other reactive chemicals, it must be handled and used with care. Chlorine gas is highly irritating to the eyes, nasal passages and the respiratory tract, and can be lethal.

The events of September 11 brought to the fore the vulnerability of many water systems to two forms of attack. One form of attack could involve disrupting or disabling the water system itself resulting in release of disinfectants such as chlorine gas to the surrounding community. Another form of attack, more insidious, could involve biological and/or chemical contamination of the drinking water.

Even before September 11, drinking water systems were acting to make their operations more secure. September 11 accelerated these enhancements: locks, guards, cameras, alarms and other basic security measures were installed in systems throughout the United States. EPA was also playing an important role in furthering efforts to protect the drinking water supply through development of a "tool kit" to assist drinking water systems to conduct vulnerability assessments and identify remedial action.

The vulnerability of drinking water systems, particularly those that rely on chlorine gas, was garnering attention by Congress as well. In a Feb. 26, 2002 letter to Administrator Whitman, Reps. Dingell, Waxman, and others, expressed their "strong concern about the level of vulnerability of our Nation's public water systems to terrorist attack or intentional acts and the consequences for the safety and health of communities served by these water systems." The letter went on to single out chlorine gas. "We are aware that approximately 2,000 public water systems in the country have notified the EPA as of November 2001 that they have more that 2,500 lbs. of gaseous chlorine on-site. These systems are located in 46 states and the District of Columbia and Puerto Rico. Gaseous chlorine, if released into the atmosphere, can become a lethal cloud with the potential to injure or kill thousands of nearby residents."

The letter' intent was quite clear B to prod EPA to recommend, if not command, water systems to replace gaseous chlorine with "safer alternatives." Ironically, the letter also strongly endorsed the utilization of vulnerability assessments by water system operators as a necessary prerequisite to initiating corrective actions, even though the letter's authors evidently were content to presume that the very presence of chlorine gas at a drinking water system should prompt corrective action. Undoubtedly, they were attempting to influence the final outcome of Title IV B Drinking Water Security and Safety of the Public Health Security and Bioterrorism Preparedness and Response Act of 2002 (Act).

Under this Act, every community water system serving more than 3,300 people is required to conduct a vulnerability assessment, examining the system's vulnerability "to a terrorist attack or other intentional acts intended to substantially disrupt the ability of the system to provide a safe and reliable supply of drinking water. The vulnerability assessment shall include, but not be limited to, a review of pipes and constructed conveyances, physical barriers, water collection, pretreatment, treatment, storage and distribution facilities, electronic, computer or other automated systems which are utilized by the public water system, the use, storage, or handling of various chemicals, and the operation and maintenance of such system." (emphasis added)

Unlike the February 26 letter to Whitman, the Act did not single out any particular disinfectant for special review or substitution by a "safer alternative." Congress clearly recognized that prejudging the outcome of a vulnerability assessment defeats the very purpose of the assessment.

Each system has until the following dates for their assessments to be certified and submitted to EPA:

• Systems serving more than 100,000 - March 31, 2003
  
• Systems serving 50,000 to 100,000 - Dec. 21, 2003
  
• Systems serving 3,300 to 50,000 - June 30, 2004

To maintain security, the assessments are to be kept in a secure location and will only be available to individuals designated by the EPA administrator. The security of these documents is obviously of utmost importance, since they in essence might otherwise provide a roadmap to terrorists intent on exploiting a system's vulnerabilities. Consequently, the Act provides for up to a year in prison or a fine to individuals convicted of knowingly or recklessly revealing any part of an assessment to an unauthorized party. Authorized individuals may discuss the assessments with state and local officials, but the community water system cannot be required to provide the assessment to those officials. However, the assessments should be available to Congress and its committees and subcommittees.

Every community water system serving more than 3,300 people is also required to have an emergency response plan that incorporates the completed vulnerability assessments within 6 months of completing the assessment. The plans shall include but not be limited to "plans, procedures, and identification of equipment that can be implemented or utilized in the event of a terrorist or other international attack on the public system … actions, procedures, and identification of equipment which can obviate or significantly lessen the impact of terrorist attacks or other intentional actions on the public health and safety and supply of drinking water." Coordination with local emergency planning committees is highly encouraged.

Importantly, the Act requires the EPA administrator to conduct various reviews of drinking water systems and ultimately share the results with drinking water systems. For example, with help from the Centers for Disease Control and Prevention, and other government agencies, EPA must review "current and future methods to prevent, detect, and respond to the intentional introduction of chemical, biological, or radiological contaminants into community water systems and source water for community water systems." These include:

• Monitoring for contaminants
  
• Providing notice of contamination to operators
  
• Developing educational and awareness programs
  
• Negating or mitigating deleterious effects
  
• Researching the impacts of contamination

As noted by Dr. Joan Rose in a recent article published in Environmental Science and Technology, water treatment, including filtration and disinfection is widely acknowledged as providing barriers to microbial contaminants. If terrorists were to engage in biological contamination of the drinking water before it is treated, filtration and disinfection could remove the threat. However, Dr. Rose notes, "there is little scientific information about what levels of reduction are possible for many potential biowarfare agents." Implementation of this Act should go a long way to filing these critical data gaps.

With regard to system-wide vulnerabilities, the EPA administrator must "review methods and means by which terrorists or other individuals or groups could disrupt the supply of safe drinking water or take other actions against water collection, pretreatment, treatment, storage, and distribution facilities which could render such water significantly less safe for human consumption." These include:

• Potential destruction of pipes and conveyances
  
• Potential destruction of collection, pretreatment, treatment, storage, and distribution facilities
  
  
• Potential alteration of pipes, conveyances, collection, pretreatment, treatment, storage, and distribution facilities

The review must also assess how the infrastructure of the drinking water system could be reasonably protected from terrorist attacks.

In short, this important Act, without prejudging the continued us of one disinfectant over another, provides the tens of thousands of drinking water systems with the requisite tools and assistance to assess their vulnerabilities and initiate corrective action.

Finally, it is worth noting that nearly all of the signatories to the February 26 letter, including both Congressmen Dingell and Waxman voted for this Act. Indeed, the House support of the Act was overwhelming, 425 Yeas, 1 Nay. The Senate vote was equally impressive, 98 Yeas, 0 Nays. It now awaits the president's signature.

David B. Fischer is managing counsel for the Chlorine Chemistry Council (CCC) and can be reached at david_fischer@americanchemistry.com, tel. 703/741-5179.. CCC is a business council of the American Chemistry Council. Jessica Stuart, a 2002 law school graduate, is working on legal issues at CCC and can be reached at jessica_stuart@americanchemistry.com.