list of largest wastewater treatment plants list of largest wastewater treatment plants the largest wastewater treatment plants can be defined in several ways.new delta treatment plant project is being developed by the largest joint venture in north africa and the middle east (mena) with experience of over 240 years in the field joined to build a new delta treatment plant (metito – orascom – arab contractor – hassan allam construction) the joint venture acted as a project manager on the client’s side. the new delta plant is being developed under the supervision of the engineering authority of the egyptian armed forces. plant name city country opening year dry-weather capacity (m³ per day) wet-weather capacity (m³ per day) area (km²) notes new delta treatment plant new delta egypt 2023 7,500,000 7,500,000 0.33 the world's largest water treatment plant 7.5 million m3/day jean-r.-marcotte wastewater treatment plant montreal canada 1984 2,780,000 7,600,000 0.67 secondary treatment planned for 2023. detroit wastewater treatment plant detroit usa 1940 2 460 000 6 435 000 0.53 wet-weather secondary treatment capacity limited to 3 520 000 m³/day. stickney water reclamation plant chicago usa 1930 2 665 000 5 450 000 1.67 deer island waste water treatment plant boston usa 1968 1 438 000 4 542 000 0.6 full secondary treatment since 1995. abu rawash wastewater treatment plant giza egypt 2021 1,600,000 13,435 secondary treatment since 2021. atotonilco de tula plant mexico city mexico 2015 2 000 000 3 000 000 hyperion water reclamation plant los angeles usa 1925 1 041 000 3 000 000 0.81 wet-weather secondary treatment (since 1950) capacity limited to 1 821 000 m³/day. kuryanovo wastewater treatment facilities moscow russia 1950 2 200 000 lyuberetskiye wastewater treatment facilities moscow russia 1963 3 000 000 seine aval wastewater treatment plant paris france 1940 1 460 000 2 900 000 8 shanghai zhuyan i wastewater treatment plant shanghai china 2004 1 700 000 stonecutters island sewage treatment hong kong china 2001 2 765 000 bailonggang wastewater treatment plant shanghai china 1999 2 000 000 gabal el asfar wastewater treatment plant cairo egypt 1 700 000 2 500 000 1.63 beckton sewage treatment works london uk 1864 2 330 000 1 morigasaki water reclamation center tokyo japan 1966 1 540 000 0.41 beijing huaifang water plant beijing china 2017 600 000 0.16 built underground. western treatment plant melbourne australia 1897 485 000 105 mcalpine creek wastewater treatment plant charlotte, n.c. usa 1966 290,950 wastewater treatment capacities are expressed in cubic meters per day. 1000 cubic meters is 1 ml (mega liter). the area occupied by the plants are in square kilometers.