Persistence and Free Chlorine Disinfection of Human Coronaviruses and Their Surrogates in Water

Abstract

The COVID-19 pandemic illustrates the importance of understanding the behavior and control of human pathogenic viruses in the environment. Exposure via water (drinking, bathing, and recreation) is a known route of transmission of viruses to humans, but the literature is relatively void of studies on the persistence of many viruses, especially coronaviruses, in water and their susceptibility to chlorine disinfection. To fill that knowledge gap, we evaluated the persistence and free chlorine disinfection of human coronavirus OC43 (HCoV-OC43) and its surrogates, murine hepatitis virus (MHV) and porcine transmissible gastroenteritis virus (TGEV), in drinking water and laboratory buffer using cell culture methods. The decay rate constants of human coronavirus and its surrogates in water varied depending on virus and water matrix. In drinking water prior to disinfectant addition, MHV showed the largest decay rate constant (2.25 day-1) followed by HCoV-OC43 (0.99 day-1) and TGEV (0.65 day-1); while in phosphate buffer, HCoV-OC43 (0.51 day-1) had a larger decay rate constant than MHV (0.28 day-1) and TGEV (0.24 day-1). Upon free chlorine disinfection, the inactivation rates of coronaviruses were independent of free chlorine concentration and not affected by water matrix, though they still varied between viruses. TGEV showed the highest susceptibility to free chlorine disinfection with the inactivation rate constant of 113.50 mg-1min-1L, followed by MHV (81.33 mg-1min-1L) and HCoV-OC43 (59.42 mg-1min-1L).