Water scarcity is the lack of adequate water resources needed to supply the demand for water in a region. Water scarcity can be a consequence of poor management of available water resources or the lack of adequate natural water sources.
Water scarcity can involve water shortage, water stress or water crisis. Water shortages occur due to a change in weather patterns, such as droughts and floods. Water stress is an occurrence where a population does not have access to drinking water and water crisis is an occurrence where there is inadequate drinking water in a region to meet the demand of its populace.
According to the United Nations, there are approximately 1 billion people globally who lack sufficient water for drinking, washing and cooking. A majority of these people live in developing countries.