Project summary
A pilot study by WRc and ADAS Biotechnology offers a clearer understanding of contamination sources in national waterbodies. The project has the potential to provide water companies with the capability of identifying and mitigating inputs of faecal pollution in rivers to support efforts to improve river health.
The background
Since 2021, only 14% of rivers in England achieved ‘good’ ecological status and none received an overall ‘good’ classification from the Environment Agency. Faecal pollution poses significant risk to human and ecological health and can originate from untreated sewage discharges, agricultural run-off and urban drainage. The research project has contributed to efforts to improve the health of national waterbodies by providing an additional means to measure the contribution of faecal contamination sources and support the application of appropriate environmental remediation strategies.
A team of water microbiologists at WRc designed, undertook and analysed samples from the River Ray in Wiltshire. DNA was extracted from the water samples for analysis by ADAS Biotechnology.
The challenge
The ability to identify specific sources of faecal contamination in UK waterbodies is important in efforts to manage and mitigate pollution. Source identification is particularly important because current regulation on microbial indicators, such as E. coli, does not distinguish between human and animal faecal sources. Through microbial source tracking, it is possible to pinpoint the specific host – humans, birds or livestock for example – opening the opportunity for more targeted water quality management.
The solution
Microbial source tracking (MST) was used to identify faecal pollution origins in the water samples using a DNA amplification technique known as quantitative polymerase chain reaction (qPCR). This technique enables researchers to detect DNA from faecal bacteria and helps to determine the specific sources of faecal pollution, such as humans or animals. The qPCR was used to detect the human-specific faecal marker HF183, the presence of which suggested contamination from specific sources of human faeces, such as sewage discharges. Elevated levels of HF183 detected downstream of a wastewater treatment works indicated human-sourced pollution in that part of the river.
The impact
Having identified a specific source of pollution to rivers, the research has made it possible to locate and manage pollution more effectively and will have a significant long-term impact on improving water quality.
Building on the success of the pilot study, microbial source tracking could be applied across various industries. The HF183 marker has proven effective in identifying human-derived faecal pollution. Future work could explore additional markers to differentiate other contamination sources, for example, targeting faecal markers specific to livestock (ruminant-specific Bacteroidales markers) could help assess agricultural run-off and its impact on water quality.