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Molecular Methods For Evaluating Eu Bathing Water Quality: A Roadmap Of Socio-economic Research Needs

Congress: 2015
Author(s): David Oliver (Stirling, UK), Richard Quilliam

David Oliver [Stirling, UK], Richard Quilliam 1

University of Stirling1

Keyword(s): Sub-theme 10: Management of water resources,


The introduction of more stringent standards associated with the revised Bathing Waters Directive (rBWD) in Europe will challenge a number of bathing water regulators across the UK in their efforts to reach sufficient microbiological status. In parallel, the use of traditional culture methods versus molecular methods to enumerate regulatory microbial parameters - Faecal Indicator Organisms (FIOs) - in bathing waters adds an extra layer of complexity to the bathing water debate. Quantitative molecular tools (e.g. qPCR) are undeniably appealing for environmental resource management because they represent a more rapid approach to determine microbial water quality. In contrast, culture-based methods currently provide a 24-48 hour turn-around time from sample analysis through to microbial water quality reporting. This has the potential for 'out-of-date' management decisions at designated bathing waters, which could have an impact on human health and/or water use. Thus, traditional culturing methods are often viewed as slow and 'out-dated' but still deliver a robust evidence-base, whereas molecular tools have significant potential, but are not yet well established enough for regulatory monitoring. As cutting edge science delivers new and more efficient technologies for microbial enumeration there comes a requirement for balanced evaluation of such approaches with regard to their operational utility and associated limitations and uncertainties. In response, a Working Group (WG) was established to bring together academics, policy makers, regulators and campaign groups from Europe and North America with the aim of building an evidence-base and decision making framework (DMF) to underpin and guide future decision making in the field of FIO enumeration in designated bathing waters.


A WG with a core membership of both science providers and science users was formed to facilitate knowledge exchange relating to cutting-edge innovative research in microbial quantification techniques for regulatory monitoring of bathing waters. Additional national and international experts from academic, regulatory, government and public organisations were invited to a series of workshops in England and Scotland to add depth and breadth to the science and policy debates under consideration. The workshop themes focused on: (i) the inherent strengths and weaknesses of different enumeration methods and future requirements in science and technological innovation; (ii) their fit to regulatory needs for monitoring bathing water compliance with particular emphasis on the contribution from diffuse catchment sources; and (iii) the economic implications of methodological transitions for the monitoring of FIOs.


Science provider and science user communities provided valuable insight into what was considered to be the most significant challenges in moving towards using molecular methods for quantifying compliance parameters at bathing waters. This included debates surrounding: inter and intra laboratory variability in recovery of organisms; cost; the lack of funding for technology development; quantification of the extra benefit gained from using such rapid methods; changes in sampling strategies and spatial & temporal implications; and the need to educate regulators/beach managers over advantages and disadvantages of molecular data. The institutional barriers that would hamper implementation of molecular techniques by regulators were also debated, as were perceived advantages of molecular tools, arguments against change, and future research needs and existing gaps in knowledge for successful implementation of qPCR as a regulatory tool for bathing water quality assessment in the EU. This also included a prioritised matrix of research needs linked to direct and indirect economic impacts of any future transition in enumeration methods for microbial compliance parameters. The WG recognized that the current requirements of the rBWD are for compliance records to be maintained and for this the speed of response with regard to understanding microbial water quality is not critical. However, speed is likely to be important for some beach users, but inflicting a methodological change on regulators when there are a number of uncertainties in the evidence-base and a diverse range of economic implications linked to a move from culture-based to molecular tools for EU bathing water regulation would not appear to be defendable at current time.


A number of key criteria were identified during this 18 month workshop series and embedded into a DMF. The development of the DMF now provides a tool to support organisations in deciding whether it is appropriate to move towards using molecular methods for compliance monitoring of bathing water quality. Developing better predictive and model-based capability was proposed as a potentially more cost-effective approach for delivering information to the public and considered to have more value to beach users than "real" (but out-of-date) water quality data.

2011 IWRA - International Water Resources Association - - Admin