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.

Key findings

1. Viruses exposed to simulated sunlight were inactivated quicker (ranging from 2 hours to 2 days) compared to viruses left in the dark
2. Without sunlight, viruses survived much longer, with decay times ranging from 14 hours to 26 days
3. 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.

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.