Wet coffee processing mills in East Africa discharge 9 million cubic meters of untreated wastewater annually with pollution loads 30-40x greater than urban sewage

Wet (washed) coffee processing -- the method used for most high-quality Arabica -- requires 1-20 cubic meters of water per tonne of fresh cherry and generates wastewater with a chemical oxygen demand (COD) as high as 50 g/L. In East Africa alone, wet mills collectively discharge approximately 9 million cubic meters of untreated wastewater and 600,000 tonnes of solid husks annually into rivers and watersheds. Why it matters: the wastewater's COD is 30-40 times the pollution load of urban sewage, so rivers downstream of processing areas become ecologically dead during harvest season (September-November), so communities that depend on those rivers for drinking water and irrigation face contaminated supplies, so waterborne disease rates increase in coffee-producing regions, so local opposition to wet mills grows and regulators threaten shutdowns, so farmers are forced toward lower-quality dry processing methods that fetch 10-20% less on the market. The structural root cause is that wet mills are operated by smallholders or small cooperatives who lack capital for wastewater treatment infrastructure, while the buyers who benefit from washed coffee's premium pricing externalize the environmental cost entirely to origin communities.