When we think about climate change, we often picture extreme weather—like scorching heatwaves and intense rain. But there’s another consequence to consider: the rising risk of infectious viruses in our waters.
As climate change brings heavier rains and more frequent heatwaves, we face an increasing chance of encountering viruses linked to sewage in rivers, lakes, and coastal areas. Heavy rain can overload sewer systems, leading to raw sewage spilling into these waterways. This untreated wastewater contains harmful microorganisms, including viruses that can pose health risks.
A recent study shows that sewage-associated viruses can linger in certain weather conditions for days. Raw sewage, teeming with waste from humans, can release billions of viral particles. While many viruses humans shed are harmless, those that cause illnesses, like enteroviruses and noroviruses, can infect many people.
The UK’s wastewater treatment methods effectively remove over 99% of these viruses. However, treated water still carries some risk, especially when raw sewage is released. This is a daily reality that poses dangers to our natural water sources.
Knowledge about how extreme weather impacts these viruses is crucial. For instance, climate projections suggest we will see more intense heatwaves similar to those in 2022, where temperatures soared to record highs.
Engagement with this challenge is ongoing. Scientists are working to understand how weather changes could enhance the infection spread from sewage-associated viruses. For example, recreational water users are already exposed to pathogens from agricultural runoff and sewage discharge, but we still need to grasp how changing weather patterns affect virus survivability and infection rates.
Research indicates that environmental samples, often contaminated with various chemicals, can complicate virus detection. My colleagues and I developed methods that isolate infectious viruses from damaged ones, improving our assessment of risk in our samples.
We conducted experiments to better understand how climate change affects these viruses. We tested how they degraded in river, estuary, and seawater under different conditions, including varying temperatures and sunlight exposure. Interestingly, the type of water—whether river, estuarine, or sea—didn’t significantly change how long the viruses remained infectious.
For instance, enteric viruses can survive in seawater for up to three days at temperatures around 30 degrees Celsius, and even longer in cooler conditions. On sunny days, virus viability drops in less than a day, compared to 2.5 days in cloudy weather. This reveals the ongoing health risks posed by sewage-associated viruses, especially during unpredictable weather patterns.
To protect yourself, it’s wise to steer clear of recreational activities in waters affected by sewage discharge for at least 2.5 days after cloudy weather, or at least 24 hours after sunny days. With climate change, the potential for sewage pollution may increase, especially after heavy rains following dry spells.
This issue isn’t just a local problem; untreated sewage discharge is a global health concern. Many countries face similar challenges. Our findings underline the urgent need for enhanced sewage treatment worldwide and highlight the importance of effective strategies to manage health risks tied to climate change.
As we navigate these changes, staying informed and proactive is more important than ever. By understanding these risks, we can better prepare ourselves and advocate for improvements in sewage treatment practices.
Jessica Kevill, Post-doctoral research associate at the School of Environmental and Natural Sciences, Bangor University
This content is republished from The Conversation under a Creative Commons license.
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