Endotoxin Water Testing of the River Taff – Insights from a Record-Breaking Cleanup
Monitoring river pollution is critical for safeguarding public health and protecting ecosystems.
Among the various indicators of water contamination, endotoxins — toxic components of the outer membrane of Gram-negative bacteria — are increasingly recognised for their role in signalling bacterial presence in aquatic environments [1].
Endotoxins can originate from natural bacterial populations, agricultural run-off, or sewage discharge, making them a potential marker for water quality assessment.
The River Taff Study
The study carried out as part of the record-breaking #TaffTidy project aimed to evaluate whether endotoxin analysis could be a practical tool for identifying pollution hotspots and tracking environmental risks. Eight water samples were collected from strategically selected locations, ranging from the relatively pristine upper reaches at Brecon to the urbanized Cardiff Barrage area.
All samples were tested using CMD’s αBET® endotoxin testing system — αBET® requires only 14 microlitres of sample with results delivered in ~10 minutes.
The measured endotoxin levels showed a notable increase downstream, especially in urban and industrial zones.
For instance, near the source of the Taff in Brecon an endotoxin level of ~77 EU/mL was observed, while samples collected at Sophia Gardens in the heart of the City of Cardiff showed a peak endotoxin concentration of > 660 EU/mL (Figure 1).
Surprisingly, levels at the Cardiff Bay Barrage dropped to ~225 EU/mL, underscoring the complexity of river dynamics and dilution effects.
Figure 1 – Results of the River Taff Study: endotoxin concentration in samples collected along the river's course.
Key Insights and Interpretation Challenges
While the study confirmed higher endotoxin levels in areas likely affected by human activity and sewage discharge, interpreting these findings is not straightforward. Several factors can influence endotoxin concentrations [2-4]:
Sample collection variables: Differences in collection methods, depth, proximity to the bank, and water flow conditions may affect results.
Environmental factors: Rainfall, river flow rate, and proximity to effluent discharge or tributaries can dilute or concentrate endotoxin levels.
Sediment influence: The type of sediment (soil, silt) and its disturbance during sampling can introduce variability, as sediments can harbour endotoxins from bacterial residues.
The Potential of Endotoxin Testing in Environmental Monitoring
Endotoxin water testing offers several advantages as an environmental monitoring tool. The method is rapid, cost-effective and accurate. Plus, endotoxin is a stable and reliable biomarker of Gram negative bacteria, which are present in high numbers in human sewage and agricultural run-off [1].
When combined with careful sampling design — such as paired sampling above and below known discharge or run-off points — it can be a valuable tool for rapidly identifying contamination events and for monitoring the effectiveness of pollution control measures.
CMD’s study illustrates that with modest resources and rigorous methodology, endotoxin testing could complement traditional chemical and microbiological assays in water quality monitoring.
The αBET® system’s ability to rapidly deliver consistent results makes it suitable for both research and regulatory applications.
Conclusion
The River Taff endotoxin study conducted by CMD demonstrates the potential of this approach in environmental science. Despite challenges in data interpretation, the findings suggest that endotoxin analysis, when combined with a thoughtful sampling strategy, can provide valuable insights into river pollution dynamics.
Further research, particularly in longitudinal studies and with controlled sampling protocols, will be essential to fully realise the potential of endotoxin testing in environmental monitoring.
References
Rojas, M., Holguin, G. & Prieto, M. A. (2021). Endotoxins in water: Sources, detection, and importance in water safety. Journal of Water and Health, 19(3): 345-356.
CMD (2025). Endotoxin analysis of 8 samples taken from the River Taff, Cardiff [Unpublished report]. Cotton Mouton Diagnostics Ltd.
Huq, A., Grim, C. J. & Colwell, R. R. (2015). Microbial indicators of water quality: A guide to understanding their use in monitoring water safety. Environmental Health Perspectives, 123(8): 775-786.
Zhang, W., Yu, Z. & Zhang, H. (2022). Sediment-associated endotoxins and their role in riverine microbial ecology. Water Research, 210: 118002.