类似地，墨西哥城被认为下水道建设水平很高的城市，但该市下水道系统将富含病菌和有毒化学物质的未经处理的废水排入梅兹奎塔尔河谷（Mezquital Valley ） ， 然后被用于灌溉庄稼。
Likewise, Mexico City is considered to have a high level of sanitation, even though it transports untreated wastewater, loaded with pathogens and toxic chemicals, to the Mezquital Valley, where it is used to irrigate crops.