World Water Day is held annually on 22 March as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources.

An international day to celebrate freshwater was recommended at the 1992 United Nations Conference on Environment and Development (UNCED). The United Nations General Assembly responded by designating 22 March 1993 as the first World Water Day.

Each year, World Water Day highlights a specific aspect of freshwater. In 2015, World Water Day has the theme "Water and Sustainable Development".

In 2016, the theme is "Water and Jobs," in 2017 "Wastewater" and in 2018 "Nature-based Solutions for Water".

Globally, the vast majority of all the wastewater from our homes, cities, industry and agriculture flows back to nature without being treated or reused – polluting drinking and bathing and irrigation and losing valuable nutrients and other recoverable materials.

Reducing and safely treating and reusing wastewater, for example in agriculture and aquaculture, protects worker, farmers and consumers promotes food security, health and wellbeing.