Every Bitcoin transaction uses, on average, enough water to fill “a back yard swimming pool”, a new study suggests. That’s around six million times more than is used in a typical credit card swipe, Alex de Vries of Vrije Universiteit Amsterdam, calculates. The figure is due to the water used to power and cool the millions of computers worldwide Bitcoin relies on. It comes as many regions struggle with fresh water shortages. Up to three billion people worldwide already experience water shortages, a situation which is expected to worsen in the coming decades, the study notes. “This is happening in Central Asia, but it’s also happening in the US, especially around California. And that’s only going to get worse as climate change gets worse,” Mr de Vries told the BBC.