WASH is an acronym that stands for the interrelated areas of Water, Sanitation and Hygiene. Being critical to human life, ensuring access to potable (clean) water for drinking is an obvious immediate priority in crisis response. Water is also critical to food preparation, maintaining sanitary conditions and preventing the spread of disease. Access to basic toilets is thus another priority in emergencies, to ensure human waste does not become a source of disease. The delivery of WASH assistance in emergencies must also take into account the development of sustainable systems. Notably, WASH is an area of constant technical innovation.