Are there concrete examples of such systems being built and operated, then just turned off?
Monitoring of sewage/wastewater for COVID case estimation Farkas, K., Hillary, L. S., Malham, S. K., McDonald, J. E., & Jones, D. L. (2020). Wastewater and public health: the potential of wastewater surveillance for monitoring COVID-19. Current Opinion in Environmental Science & Health, 17, 14-20. Daughton, C. G. (2020). Wastewater surveillance for population-wide Covid-19: the present and future. Science of the Total Environment, 736, 139631. Bogler, A., Packman, A., Furman, A., Gross, A., Kushmaro, A., Ronen, A., ... & Bar-Zeev, E. (2020). Rethinking wastewater risks and monitoring in light of the COVID-19 pandemic. Nature Sustainability, 3(12), 981-990. Jaiswal, R., Agarwal, A., & Negi, R. (2020). Smart solution for reducing the COVID‐19 risk using smart city technology. IET Smart Cities, 2(2), 82-88.