Written Reply by Ms Grace Fu, Minister for Sustainability and the Environment, to Parliamentary Question on Waste Handling in Housing Estates and Hospitals
Ms Mariam Jaafar: To ask the Minister for Sustainability and the Environment what precautions have been introduced for waste handling in housing estates and hospitals in light of the detection of viral fragments in wastewater samples in clusters like the Bukit Merah cluster.
1 Stringent measures are in place in Singapore to prevent the transmission of COVID-19 through wastewater. Viral particles could enter the wastewater streams from toilets, where infected individuals could shed the virus through sputum and in their stool. Viral particles could also have been present in toilets as bioaerosols due to the expired air of infected individuals when they cough, sneeze, or talk or from the flushing of cisterns, and on surfaces touched by these individuals. The National Environment Agency has been working with premises owners to disinfect premises thoroughly, including toilets where COVID-19 patients have visited to ensure that premises are safe.
Sanitary system design in Singapore
2 The sanitary systems in Singapore are also designed as “closed systems”, where pipes are airtight and watertight to ensure that no foul air or pathogens can travel between households within the building. The sanitary system of each bathroom is designed with water seals which act as barriers to prevent foul air containing pathogens in the sanitary system from entering a unit’s premises. These water seals, located in toilet bowls and floor traps, are maintained by regular water flow from sinks, wash basins, showers or flushing of water cisterns. These are mandatory design requirements for sanitary systems and they apply to all toilets and bathrooms in Singapore.
3 However, as with all well-designed systems, it requires maintenance. Home owners should be on the lookout for sewage odour and signs of localised failures within their premises such as leaks from toilet bowls or sanitary pipes. Owners should promptly get professional help through Licensed Plumbers to check and rectify any faults.
Treating wastewater at isolation facilities
4 In terms of wastewater from hospitals, there are existing requirements for the wastewater from isolation facilities for infectious diseases to be disinfected before they are discharged into the public sewer. These are precautionary measures as the COVID-19 virus will degrade in the used water network.
5 As an added measure, operation staff involved in used water treatment, such as those at water reclamation plants are required to don personal protective equipment such as masks, gloves and face shields to ensure that they are fully protected from direct exposure to wastewater.
Water supply remains unaffected
6 The quality of our water supply will not be affected as the collected wastewater undergoes a rigorous process in its journey to become NEWater. The NEWater goes through stringent treatment and disinfection processes, which remove all contaminants and ensure all bacteria and viruses are killed. To help visualise the reverse osmosis process in the NEWater production, the pores of the reverse osmosis membrane are so small that if magnified 100 million times, they will be comparable to the size of tennis balls, while the virus will be the size of a truck. Notwithstanding, further safety barriers such as UV and chlorine disinfection are incorporated downstream to ensure the safety of our NEWater supply.
7 With these measures in place, I would like to assure Singaporeans that there is minimal risk of the COVID-19 virus transmitting through the wastewater system.