Bathing water status may be impossible through wastewater improvements alone, experts warn

Researchers have highlighted a shortfall in understanding of the impact of agricultural run-off on river and coastal water quality which may obstruct efforts to achieve bathing water status through improved wastewater outflow alone.

Scientists at UK Water Industry Research (UKWIR), in a review of risks associated with treated and untreated wastewater have described “the significant impact agricultural inputs which may mean bathing water status cannot be achieved, irrespective of wastewater end-of-pipe interventions (for example, disinfection).”

They added: “Risks form sewage derived versus agricultural or industrial pathogen loads remains unknown.”

The researchers recommended additional work using existing bacterial and other microbial indicators of river quality as well as other interventions such as “nature-based solutions and agricultural best-management practices.”

Other recommendations included studies to improve the evidence base for new microbial indicators possibly including viral pathogens. UKWIR emphasised the possible growing importance of viral loads

In the light of “an emerging focus on water reuse in the UK.”

Meanwhile the researchers maintain that the water sector should retain existing microbial standards, which are aligned with best-science and latest World Health Organisation and European Commission reviews. They point out in the report that the there are no current recommendations from experts globally to move to viral indicators. Reason include the strong evidence base for the faecal indicator organisms used currently and multiple challenges including sampling, precision in counting and “highly variable concentrations” of viral material.