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

Abstract. Continually improving and affordable wastewater management provides opportunities for both

pollution reduction and clean water supply augmentation, while simultaneously promoting

sustainable development and supporting the transition to a circular economy. This study aims to

provide the first comprehensive and consistent global outlook on the state of domestic and

manufacturing wastewater production, collection, treatment and reuse. We use a data-driven approach,

collating, cross-examining and standardising country-level wastewater data from online data

resources. Where unavailable, data are estimated using multiple linear regression. Country-level

wastewater data are subsequently downscaled and validated at 5 arcmin

(∼10 km) resolution. This study estimates global wastewater production at 359.4×109 m3 yr−1, of which 63 % (225.6×109 m3 yr−1) is

collected and 52 % (188.1×109 m3 yr−1) is treated. By extension, we

estimate that 48 % of global wastewater production is released to the environment untreated,

which is substantially lower than previous estimates of ∼80 %. An estimated 40.7×109 m3 yr−1 of treated wastewater is intentionally reused. Substantial

differences in per capita wastewater production, collection and treatment are observed across

different geographic regions and by level of economic development. For example, just over 16 %

of the global population in high-income countries produces 41 % of global wastewater. Treated-wastewater reuse is particularly substantial in the Middle East and North Africa (15 %) and

western Europe (16 %), while comprising just 5.8 % and 5.7 % of the global population,

respectively. Our database serves as a reference for understanding the global wastewater status

and for identifying hotspots where untreated wastewater is released to the environment, which are

found particularly in South and Southeast Asia. Importantly, our results also serve as a baseline

for evaluating progress towards many policy goals that are both directly and indirectly connected

to wastewater management. Our spatially explicit results available at 5 arcmin

resolution are well suited for supporting more detailed hydrological analyses such as water

quality modelling and large-scale water resource assessments and can be accessed at

https://doi.org/10.1594/PANGAEA.918731 (Jones

et al., 2020).