In 2017, the theme was “Why Waste Water?” which was about reducing and reusing wastewater.[7] The theme was a play on words as it related to both the aspect of wasting water and issues around wastewater, namely treatment and reuse. Wastewater is a valuable resource to help achieve the Sustainable Development Goal Number 6. One aspect of Target 6.3 is to halve the proportion of untreated wastewater and also to increase the recycling and safe reuse of water across the globe. After appropriate treatment, wastewater can be used for a variety of purposes. Industry, for example, can reuse water in cooling towers and agriculture can reuse water for irrigation.[22]

An example activity for 2017 was the Wikipedia edit-a-thon organized by members of the Sustainable Sanitation Alliance on 19–21 March 2017. The purpose of the activity was to improve water and sanitation related content on Wikipedia just ahead of World Water Day. The goal was to improve the quantity and quality of sanitation information available on Wikipedia for the use of teachers, journalists and the general public.[23]