During water system interruptions, the operation of health care facilities is severely interrupted and capability can be almost completely degraded within two hours. In order to maintain daily operations and patient care services, health care facilities need to develop a water supply plan in advance of an emergency. Several types of events such as a natural disaster, a failure of the community water system, construction damage, or even an act of terrorism can cause water supply interruption. Because water supplies can and do fail, it is imperative to understand and address how patient safety, quality of care, and the operations of your facility will be impacted. This 2019 revised guide can provide a road map for health care facilities to prepare for, respond, and recover from a total or partial water supply interruption by providing the guidance to assess water usage, response capabilities, and water supply alternatives. The planning guide was published as a collaborative effort between CDC, the Environmental Protection Agency (EPA) and the American Water Ways Association (AWWA).