In the past 20 years, we have seen several viral outbreaks including Ebola, Swine Flu, SARS-CoV-1 and MERS-CoV. Due to the increased number of animal virus outbreaks in humans, wastewater surveillance is an effective method to discover and track viral infections in humans. Being effective and cheaper than mass testing, wastewater testing is essential as an early screening system.
The SARS-CoV-2 virus can remain infectious for days and even longer in sewage and drinking water. Viruses can be transmitted through coughing or sneezing but they can also be transported in microscopic water droplets or aerosols. Airborne transmission via aerosols can occur over an extended distance and time. Viruses present in aerosols can deposit directly along the human respiratory tract.
Traces of Covid-19 have been detected in sewage treatment plants throughout the world. It is expected that this will be ongoing where there are active cases in the community. Although there has been no report of faecal-oral transmission, it is conceivable that it can become a channel of transmission if the wastewater is not treated properly or dispersed above ground.
Previous studies have shown that the virus can survive in wastewater for hours and even days without disinfection, and there have been reports[iv] that indicated sewage was a cause for the spread of SARS in Hong Kong in 2003. However, chlorine dosing, similar to that employed at the MWRD’s Calumet, Egan, Hanover Park and Kirie Water Reclamation Plants (WRPs), has been said to be “sufficient to control the virus,” according to WEF.
Millions of Australians have installed on-site sewage facilities (OSF) in their homes. In Queensland alone, we have over 300,000 on-site sewerage systems like septic systems and aerated wastewater treatment plants. These systems use pumps and mechanical systems to treat sewage and disperse the treated effluent above the ground.
While many OSF are usually not well-maintained and may not be able to kill bacteria and viruses and the quality of resulting treated wastewater as such cannot be guaranteed. These systems may potentially become a source of contamination if not managed correctly.
Regular maintenance is crucial to ensure that the system is working properly and removing the pathogens before above-ground dispersal. Unless your system is well-maintained, you cannot guarantee the quality of effluent or know if there’s any viable virus present in the system or not. Wastewater should be treated in a properly designed and well-maintained system to ensure there's minimum risk of spreading and catching a potentially infectious disease. Ensure you get your OSF system tested and pumped out regularly by a licensed wastewater professional.