Concerns arose about the SARS-CoV-2 virus and its presence or survival in various water environments. Understanding its behavior in different settings, particularly water sources people encounter daily, became a natural area of inquiry to clarify potential risks associated with water.
SARS-CoV-2 Survival in Aquatic Environments
The SARS-CoV-2 virus, primarily a respiratory pathogen, exhibits limited viability in aquatic environments compared to its airborne transmission. Its persistence in water depends on several factors, including temperature, the presence of disinfectants, and organic matter. Studies indicate that infectious SARS-CoV-2 generally survives for shorter periods in water than its genetic material, RNA, which is more stable but does not indicate infectivity.
Infectious SARS-CoV-2 shows reduced survival at higher temperatures; for example, it remains viable significantly longer at 4°C than at 20°C in both fresh and seawater. Specific research found infectious SARS-CoV-2 had a 90% reduction time of about 1.7 days in tap water at room temperature, 2.3 days in river water at 20°C, and approximately 1.1 days in seawater at 20°C. The presence of organic and microbial matter in water can also reduce viral survival, although suspended solids might offer some protection to the virus.
COVID-19 Transmission Risk from Recreational and Drinking Water
Current evidence suggests a very low risk of contracting COVID-19 from recreational water or drinking water. The virus has not been detected in treated drinking water supplies, and conventional water treatment processes, which include filtration and disinfection, effectively remove or inactivate the SARS-CoV-2 virus. This ensures that tap water remains safe for drinking, cooking, and hygiene.
Similarly, the risk of transmission through recreational water, such as swimming pools, hot tubs, and splash pads, is considered very low. Proper water disinfection with chlorine or bromine effectively inactivates the virus in these settings. Research shows standard swimming pool water conditions, with appropriate chlorine levels (e.g., 1.5 mg per liter free chlorine) and pH (between 7 and 7.2), can reduce SARS-CoV-2 infectivity by over 1000-fold within 30 seconds. For natural bodies of water like lakes, rivers, and oceans, there is no evidence of the virus spreading through the water itself; the large volume and movement of water in these environments contribute to dilution, making infection from the water unlikely.
Understanding Wastewater and COVID-19
SARS-CoV-2 genetic material can be detected in human waste, leading to its presence in municipal wastewater. Infected individuals, even those who are asymptomatic, can shed viral RNA in their feces, allowing for its detection in untreated wastewater sometimes before symptoms appear.
Wastewater surveillance has become a valuable public health tool for monitoring community viral loads and identifying trends in COVID-19 circulation. It can provide an early indication of infection levels within a community, sometimes days before clinical cases are reported. The detection of viral RNA in wastewater does not mean the virus is infectious; it indicates the presence of genetic fragments. Standard wastewater treatment processes are generally effective at inactivating the SARS-CoV-2 virus, significantly reducing its presence in treated effluent.
General Water Safety and Hygiene Practices
Maintaining good general hygiene and water safety practices remains important for preventing various illnesses, regardless of the low risk of waterborne COVID-19 transmission. Regular and thorough handwashing with soap and water for at least 20 seconds is recommended, especially after using the restroom and before preparing food. If soap and water are not available, an alcohol-based hand sanitizer with at least 60% alcohol can be used.
When enjoying recreational water, it is advisable to avoid swallowing water from pools, lakes, or oceans. These foundational hygiene practices promote public health by reducing the spread of many common pathogens.