Abstracts Prevention is the most basic component of a defense-in-depth approach to water security. All aspects of the water supply, treatment, and distribution system are vulnerable to attack, necessitating protection at all levels. Maintaining physical barriers, such as alarms, fences, and locks reduces the likelihood of threats to water systems while securing valuable facility property. Other effective methods to improve water security include employee screening and training. The lack of U.S. EPA regulations and federal funding for preventative water security strategies reduces the adoption rate of modern security features. Therefore, it is important that innovative and cost-effective dual-use technologies and planning strategies be developed to compensate for the large investment required to implement such strategies.