What’s in the Pipeline? Evidence on the Transmission of SARS-CoV-2 via Building Wastewater Plumbing Systems

There is emerging evidence of the transmission of SARS-CoV-2 via the sanitary plumbingwastewater system, a known transmission pathway of SARS-CoV-1. These events can nolonger be dismissed as isolated cases, yet a lack of awareness and of basic researchmakes it impossible to say just how widespread this mode of transmission might be. Virusis transmitted within wastewater systems by the aerosolisation of wastewater andsubsequent transport of bioaerosols on naturally occurring airflows within the pipednetwork. Central to the debate around risk to building occupants from SARS-CoV-2spread via wastewater plumbing systems is the question of infectivity of faeces, urine andassociated aerosols. This paper presents an examination of the processes which underliethis mode of transmission, and the existing epidemiological evidence, as well as existingmitigation strategies; significant gaps in the state of the knowledge are also identified. It ishoped that this review will cultivate a wider awareness and understanding of this most overlooked of threats, and to facilitate the selection and adoption of appropriate mitigation strategies. Key gaps in the knowledge span the rate of generation of bioaerosols within the building drainage system, their composition and transport properties, and the viability and infectivity of virions and other pathogens which they carry. While much of this work will be conducted in the laboratory, we also identify a dearth of field observations, without which itis impossible to truly grasp the scale of this problem, its character, or its solution.