Reliable, resilient, and secure water infrastructure is critical to ensure that water sources and water distribution systems are protected from natural disasters and intentional disruptive events. Researchers at Sandia National Laboratories have developed decision support tools to address the complex challenges that face water infrastructure. This work was motivated by the signing of Homeland Security Presidential Directive 9 (HSPD-9) by President G.W. Bush in 2004 that called for more rigorous monitoring and assessment our nation’s water sources and distribution systems after 9/11. Sandia’s water security software packages (in parentheses below) are designed to help decision makers design more effective monitoring, response, and restoration strategies for water distribution systems.