Water Security

Intentional dissemination of biological, chemical, or radiological agents through drinking water distribution systems has become an issue of particular concern—over and above the physical threats to drinking water and wastewater infrastructure (treatment plants, pumping stations, pipelines and disinfectant storage facilities).  

Priority pathogens have been organized into Categories A-C by the Centers for Disease Control and Prevention and the National Institute of Allergies and Infectious Diseases.

For more information, please review this comprehensive list of categories.

• VX
• O-Ethyl-S-(N 3 N-dimethylaminoethyl)
• Methyl thiophosphonate
• Sarin
• Colchicine
• Cyanide, amiton
• Fluroroethanol
• Sodium fluoroacetate
• Selenite
• Arsenite
• Arsenate

See also the CDC's list of chemical agents.

Conventional surface-water/drinking-water treatment plants consist of multi-barrier treatment systems that can effectively reduce microbiological and chemical loads potentially present in source waters. (See the Environmental Protection Agency's History of Drinking Water Treatment.)

Surface water treatment typically consists of

• Coagulation
• Flocculation
• Sedimentation
• Filtration
• Disinfection 

Treated water exiting the water treatment plant contains a residual disinfectant to reduce potential microbiological risks posed by microorganisms inadvertently entering the distribution system.

How likely is the contamination of our water supply?
The enormous dilution capacity of most source waters would make it extremely challenging to deliver sufficient levels of a harmful agent into a drinking water treatment plant’s raw water supply. 

Intentional alteration of control mechanisms
Of greater concern is the introduction of contaminants into a municipal drinking water distribution system. A large city contains thousands of miles of drinking water pipes and multiple pumping stations. The potable water in these pipes is under constant pressure to provide continuous source of water for domestic, industrial and fire-suppression use. At critical junctions within the distribution system, control mechanisms (valves, diverters, etc.) have been installed to prevent the inadvertent backflow of non-potable water into the system. Intentional alteration of these mechanisms could provide a means of contaminating a small portion of the distribution system with an introduced agent.

Testing water quality
Classical tests to determine changes in water quality within a distribution system include heterotrophic plate counts, pH, color, chlorine residual, turbidity and conductivity. These tests may not necessarily indicate a hazard but will indicate a change in water quality. Other more sophisticated tests, conducted either on-line or by obtaining a grab sample for analysis in a laboratory, would be required to verify the hazard.

Additional Resources
http://www.epa.gov/safewater
The EPA's Office of Ground Water and Drinking Water (OGWDW) is responsible for overseeing implementation of the Safe Drinking Water Act and protecting public health by ensuring safe drinking water and protecting ground water.

http://www.waterhealthconnection.org/index.asp
Sponsored by the American College of Preventive Medicine, this Physician On-Line Reference Guide provides informational resources and educational tools to assist in the recognition of waterborne disease and the health effects of water pollution.

http://www.nesc.wvu.edu/ndwc/ndwc_protect.htm
The National Drinking Water Council has assembled information about protecting small water systems against potential threats.

http://water.usgs.gov/owq/
The United States Geological Service, Office of Water Quality provides leadership and coordination in the development of programs to address issues concerning the quality of the nation's surface-water and ground-water resources and provides support in the application of techniques for the collection, analysis and interpretation of water-quality data.

http://www.nlm.nih.gov/medlineplus/drinkingwater.html
Medline Plus is a service of the National Library of Medicine. The drinking water section provides a resource for water-related information including water safety.

http://www.atsdr.cdc.gov/hazdat.html
HazDat, the Hazardous Substance Release/Health Effects Database of the CDC's Agency for Toxic Substances and Disease Registry, is the scientific and administrative database developed to provide access to information on the release of hazardous substances from Superfund sites or from emergency events, as well as on the effects of hazardous substances on the health of human populations.

http://www.awwa.org/advocacy/learn/sECURITY/
This training was developed through partnership with American Water Works Association (AWWA). It covers the entire spectrum of drinking water security issues, including assessing vulnerabilities, emergency response plans and risk communication.