The funniest maths in modern environmentalism. One almond requires 12 litres of irrigated water to produce. Peer-reviewed, ScienceDirect, 2017. A glass of almond milk contains roughly 50 of them. 600 litres of water before the carton is filled. The water comes from the San Joaquin Valley in California, which sits over one of the most over-extracted aquifers on earth. The valley floor has subsided by up to nine metres in places due to groundwater depletion. The carton is then refrigerated, sailed across the Atlantic, refrigerated again, lorried to a Manchester Tesco, and bought by someone who is concerned about the environmental impact of dairy. Meanwhile, in Cheshire. A British dairy cow drinks roughly 70 to 100 litres of water a day and produces around 28 litres of milk. That's about 3.5 litres of water per litre of milk. The water is rainwater that fell on her field or came from a local stream fed by the same rainwater. The rain was going to fall on the field whether the cow stood in it or not. 80% of her moisture intake comes from the grass itself, which is also rain. She converts the grass, free of charge, into a litre of milk containing seven times the protein and four times the calcium of almond milk, and shipped roughly 18 miles to the same Tesco. To recap. 600 litres of stolen aquifer, flown halfway round the world for nutritionally worthless beige water. Or 3.5 litres of rain that was already falling, converted by an animal you can pet, into actual food. The shopper picks the almond. She has been told this is the ethical position. The aquifer would like a word.