With the outbreak of COVID‐19, wastewater surveillance for public health rapidly emerged and expanded globally. In this article we chart the variegated ecosystem of private firms that work closely with public and non‐profit entities to transform metabolic flows of sewage into vital and valuable bioinformation, thereby creating new multi‐institutional spaces of public health governance. We draw on literature in urban political ecology and political economy to ask: what are the emerging political economic actors, practices, and relations of wastewater surveillance? And how are emergent multi‐institutional public‐private partnerships and contracts transforming public health governance? To answer these questions, we use mixed qualitative methods to trace the field across North America, the Middle East and South Asia. Drawing on interviews, document and report reviews, financial reporting and observation at conferences, we find that these emerging public‐private partnerships present concerning transformations in health governance where profits displace public health needs, proprietary technologies blackbox public health decisions, and vulnerable populations are experimented on for prototyping technology. Our work contributes to renewed interest in urban political ecology's analysis of metabolism by tracing how, during health crises and their aftermath, public and private actors are together reconfiguring flows of waste, labour and technology to unlock new metabolic reservoirs of bioinformation.