I am brushing my teeth. I reach across to turn off the tap, as advised by the water conservationists. In the field at the back of the house, the irrigators are chucking thousands of gallons of water onto the potato crop.
We are told that sometime soon – in this century probably – the planet will run out of water. How can this be, I wonder, when earth is a closed system? Water circulates. It evaporates and comes back as rain; it seeps down to the water table and comes back through our taps; it flows back into rivers from effluent plants. How is is possible that it can run out?
I reflect that I don’t have enough understanding of physics, or even or geography. Why is drought? Boiled water becomes steam and condenses back into water. If the water molecule is somehow split into hydrogen and oxygen, does that molecule of water disappear for ever? And how might this happen? I consult with my step-grandson, who tries to explain how, with global warming, water will remain suspended in the atmosphere and never fall again as rain.
My human body is 60% water and, whilst it circulates, this amount effectively remains trapped. If this body is cremated, is this water lost to the system? If it is buried, is the water reclaimed? And does the amount of carbon released either way mitigate any gains? If the human and animal population of the world increases, does too much water get trapped in bodies, so that it is not available for the planet?
If humans start to use de-salination plants extensively, will the oceans become too salty for marine life to survive? When the icecaps melt and polar species are devastated, will this nevertheless mean more available water? Or will it mean that the planet heats up so much that life can’t survive anyway?
How fortunate we are to live in a time when streams still bubble down the hillsides and waterfalls plunge over rocks. How fiercely we must appreciate a draught of clear, clean tap water with a cube of ice clinking against the glass and condensation gathering on the outside.
How sweet the falling rain.