Sunlight and UV rapidly reduces viruses in sewage contaminated water
A new study has revealed the crucial role of sunlight, specifically UV radiation, in rapidly reducing the presence of harmful viruses in sewage-contaminated seawater.
Researchers at Bangor University found that exposure to sunlight significantly accelerated the decay of viruses such as Adenovirus, Enterovirus, and Norovirus in rivers, estuaries, and seas.
Sewage spills are a serious health risk, especially when they get into natural waters like rivers, estuaries, and the sea. These waters can easily carry viruses that can spread and make people sick, especially when conditions allow these viruses to survive and spread.
Research highlights:
- Viruses exposed to simulated sunlight were inactivated quicker (ranging from 2 hours to 2 days) compared to viruses left in the dark.
- Without sunlight, viruses survived much longer, with decay times ranging from 14 hours to 26 days
- Understanding how viruses persist and decay can help assess risks and improve strategies for keeping public water supplies safe.
This research highlights the benefits of sunlight in keeping our water safe from viral contamination and the need to develop new water management strategies in vulnerable regions experiencing cooler, wetter climates where sewage spills occur.
Lead researcher, Dr Jessica Kevill is one of BlueAdapt’s virologists from the University of Bangor. Kevill said: “These findings are crucial for understanding how to better manage coastal water quality after sewage spills. Areas with sufficient sunlight may see faster viral reductions, while shaded or deeper waters may need more attention to ensure viruses don’t linger.”
Full citation
Jessica L. Kevill, Kate Herridge, Xiaorong Li, Kata Farkas, Shelagh K. Malham, Peter Robins, Davey L. Jones, Comparative impact of sunlight and salinity on human pathogenic virus survival in river, estuarine, and marine water microcosms, in Water Research, Volume 278, 2025, 123411, https://doi.org/10.1016/j.watres.2025.123411.
