All life needs water. It is the world's most precious resource, essential for producing the food we eat, growing the cotton we wear, and in many countries driving the energy we use. We're even made of it: the average human is 60 percent water.
Freshwater habitats-such as lakes, rivers, streams, and wetlands-house an incredible proportion of the world's biodiversity: more than 10 percent of all known animals and about 50 percent of all known fish species.
Yet despite the massive role water plays for people and nature, it is a finite resource. Part of the problem is that only 3 percent of the world's water is freshwater, and less than one percent of that is freely available; the rest is frozen - caught up as glaciers, snowcaps and icebergs.
Our demands on freshwater are growing much faster than it pours from our taps. In March 2015, the United Nations revealed that in the next 15 years we face a 40 percent shortfall in water supplies globally as a result of increasing populations, urbanisation and increasing demands from industrial production. Climate change is altering patterns of weather and rainfall around the world, causing shortages and droughts in some areas and floods in others.
New Zealand is not immune either. Although we have a high average annual rainfall of 550 billion cubic metres - enough to fill Lake Taupo nine times over - we have a growing problem with water quality. According to 2013 Environment Ministry figures, more than 60 percent of monitored rivers in New Zealand are unsafe for swimming. Worse still, New Zealand's wetlands occupy just 10 percent of their original extent.