To inform the development of global wastewater monitoring systems, we surveyed programmes in 43 countries. Most
; programmes monitored predominantly urban populations. In high-income countries (HICs), composite sampling at
; centralised treatment plants was most common, whereas grab sampling from surface waters, open drains, and pit
; latrines was more typical in low-income and middle-income countries (LMICs). Almost all programmes analysed
; samples in-country, with an average processing time of 2·3 days in HICs and 4·5 days in LMICs. Whereas 59% of
; HICs regularly monitored wastewater for SARS-CoV-2 variants, only 13% of LMICs did so. Most programmes share
; their wastewater data internally, with partnering organisations, but not publicly. Our findings show the richness of
; the existing wastewater monitoring ecosystem. With additional leadership, funding, and implementation frameworks,
; thousands of individual wastewater initiatives can coalesce into an integrated, sustainable network for disease
; surveillance—one that minimises the risk of overlooking future global health threats.