Country-level and gridded estimates of wastewater production, collection, treatment and reuse

Abstract

Abstract. Continually improving and affordable wastewater management provides opportunities for both\npollution reduction and clean water supply augmentation, while simultaneously promoting\nsustainable development and supporting the transition to a circular economy. This study aims to\nprovide the first comprehensive and consistent global outlook on the state of domestic and\nmanufacturing wastewater production, collection, treatment and reuse. We use a data-driven approach,\ncollating, cross-examining and standardising country-level wastewater data from online data\nresources. Where unavailable, data are estimated using multiple linear regression. Country-level\nwastewater data are subsequently downscaled and validated at 5\u2009 arcmin \n( ∼10\u2009km ) resolution. This study estimates global wastewater production at 359.4×109 m3\u2009yr−1 , of which 63\u2009% ( 225.6×109 m3\u2009yr−1 ) is\ncollected and 52\u2009% ( 188.1×109 m3\u2009yr−1 ) is treated. By extension, we\nestimate that 48\u2009% of global wastewater production is released to the environment untreated,\nwhich is substantially lower than previous estimates of ∼80\u2009% . An estimated 40.7×109 m3\u2009yr−1 of treated wastewater is intentionally reused. Substantial\ndifferences in per capita wastewater production, collection and treatment are observed across\ndifferent geographic regions and by level of economic development. For example, just over 16\u2009%\nof the global population in high-income countries produces 41\u2009% of global wastewater. Treated-wastewater reuse is particularly substantial in the Middle East and North Africa (15\u2009%) and\nwestern Europe (16\u2009%), while comprising just 5.8\u2009% and 5.7\u2009% of the global population,\nrespectively. Our database serves as a reference for understanding the global wastewater status\nand for identifying hotspots where untreated wastewater is released to the environment, which are\nfound particularly in South and Southeast Asia. Importantly, our results also serve as a baseline\nfor evaluating progress towards many policy goals that are both directly and indirectly connected\nto wastewater management. Our spatially explicit results available at 5\u2009 arcmin \nresolution are well suited for supporting more detailed hydrological analyses such as water\nquality modelling and large-scale water resource assessments and can be accessed at\n https://doi.org/10.1594/PANGAEA.918731 (Jones\net al., 2020).