Climate change impacts on water are well documented, from floods to droughts hydrological climate impacts affect the lives and livelihoods of millions of people around the world. One aspect of the issue that is, perhaps, less well reported is that of climate impacts on wastewater. In an effort to correct this, the UN has made wastewater its theme for this year's World Water Day.

The issue of wastewater and water reuse is becoming increasingly important. The vast majority of wastewater entering the natural environment untreated, and with millions of people, mostly in developing countries, forced to drink wastewater that is contaminated with human faeces, the issue has serious implications for health and development.

The recent UN Sustainable Development Goals (SDGs) set a target for reducing by half, the amount of wastewater that enters the environment untreated by the year 2030. But what can be done to achieve this? And how might climate change impact wastewater treatment and reuse?

To find out more Acclimatise spoke with Johannes Cullmann, Head of Climate and Water at the World Meteorological Organisation (WMO).