Wastewater treatment & recycling (~56% treated) sits within Water, the item more essential than any traded good, yet the least marketized on this list — a category with a real, cited scale: $1.04T infrastructure investment need for universal water access and sanitation by 2030 (World Bank). Wastewater treatment & recycling (~56% treated) is one of 14 of the category's 20 items directly backed by FAO AQUASTAT, WHO/UNICEF JMP, UN Stats SDG indicators, ICOLD, and the International Hydropower Association's tracked datasets, rather than an editorial judgment call.
Wastewater treatment & recycling (~56% treated) is 1 of 20 items in Water. See the full ranked list, or browse all 20 Human Endeavors categories.