Every tonne of food rotting away in an African landfill carries a water bill no-one asks you to pay. But unlike the hidden value in waste-to-energy, this hidden water bill is detrimental to water-stressed regions, which is pretty much the whole of Africa.
Today (29 September) marks the UN’s International Day of Awareness of Food Loss and Waste, but for Africa’s water planners, the paramount number is the water used to grow food that gets wasted.
Sub-Saharan Africa loses 23% of its food between harvest and retail. This is the highest rate of any region, according to the Food and Agriculture Organization’s (FAO) 2025 Food Loss Index.
Most of that loss happens on farms and in storage, or, in some regions, because of a lack of cold-storage solutions.
Food waste is water waste
The FAO estimates that food not eaten consumes about 250km³ of blue water (irrigation, surface and groundwater) every year. For a visual, 250km³ represents almost three times the volume of Lake Geneva, or the annual water discharge of the Volga River.
The FAO estimate draws on 2007 data but remains the standard global benchmark.
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Consumer-avoidable food waste accounts for 82 billion m³ of water and about four exajoules of energy a year, according to a 2021 study in the Journal of Cleaner Production.
The gains from fixing this are substantial. A 2021 review in Frontiers in Sustainable Food Systems found that halving food loss and waste could cut the water footprint of global food production by 12–13% and ease water scarcity for more than 720 million people.
The South African picture
South Africa loses or wastes an estimated 10.3 million tonnes of edible food a year. That is 45% of its available food supply, according to Council for Scientific and Industrial Research (CSIR) research led by Prof Suzan Oelofse.
WWF-SA calculates that the water embedded in that wasted food would fill more than 600,000 Olympic swimming pools. The energy used to produce it could power Johannesburg for about 16 weeks, at a cost of roughly R1 billion in diesel and electricity.
Have you read? The smartest litre is the one you already have
The timing could hardly be worse. Agriculture uses 60–62% of the country’s water, and demand already exceeds supply, Water Research Commission CEO Dr Jennifer Molwantwa warned in July.
She expects the gap to reach 17% by 2030, and every litre spent on binned food widens that gap. Maybe think on that the next time you toss an uneaten meal into the bin.
