Rapid detection of faecal pollution in bathing water

During nice weather, people increasingly take to the water for bathing and leisure, sometimes in large numbers. Cities, municipalities, water authorities and Rijkswaterstaat do their best to make urban water and designated bathing locations accessible and suitable for leisure use, and for sports and charity events like City Swims. Public confidence that bathing water is healthy is extremely important. Nevertheless, bathers have fallen ill as a result of severe pollution due to faecal matter, blue-green algae or rat urine. Furthermore, pollution peaks also pose problems for bathing water managers: beaches may lose Blue Flag certification. Rapid measurement methods that can detect variations in water quality quickly and clearly are needed to limit the risk for bathers. But today’s measurement methods are not fast enough and so more accurate methods are needed.

Technology

Information about the microbial water quality in rural and urban areas is needed to support decisions about public events. This also applies to the current situation regarding the safety of bathing water, including communications for bathers. Better and quicker monitoring of water quality means that leisure activities and events can be safe. In this project we compare conventional methods with new, rapid methods for detecting faecal pollutants in bathing water. In addition to use in field measurements, the methods were validated briefly in the laboratory. This involves determining the detection thresholds of the methods, and assessing the measurement results on the basis of the guidelines for bathing water quality. The methods were also studied to see whether they can be used for surface water at different locations.

Challenge

In the first subproject, the water was tested at eleven bathing locations for the presence of E. coli, blue-green algae toxin genes, and Leptospira (Weil’s disease) using Orvion’s mobile qPCR method (Orvion UDetect). The results were compared with those of the conventional MPN method and the lab-based qPCR method for all three parameters. The second subproject used the BACT control sensor at several locations – the canals of Breda, the Waal river at Nijmegen, and the Marineterrein in Amsterdam – for the continuous monitoring of E. coli. The third subproject compared two innovative mobile qPCR methods (Orvion UDetect and Primerdesign’s Sopachem Genesig Q16) and the BACT control sensor with the MPN method in a laboratory validation.

Solutions

The validation experiments in subproject 3 showed that there is a reasonable correlation between the mobile qPCR, BACTcontrol and standard MPN methods. Subproject 1 demonstrated that UDetect’s mobile qPCR can be used to simultaneously determine the presence of E. coli and blue-green algal toxin genes in bathing locations. As a result, qPCR with mobile qPCR methods of this kind is possible in the field without specialised resources. The field tests in subproject 2 have shown that the BACTcontrol would seem to be suitable for the detection of major faecal contaminations of bathing water that exceed the acute limit of 1800 E. coli/100 ml. However, the BACTcontrol is not suitable for detecting infections when the bathing water can be used again by leisure visitors. The mobile qPCR approach can be used for this purpose.

This provides a set of rapid methods that water managers can use to investigate the presence of faecal contaminants in surface waters. This project has established enough confidence and openings to use the methods at other locations, and particularly unofficial bathing locations, and to establish whether, when and to what extent faecal contaminants are present.

With a rapid on-site method to determine the actual bathing water quality on the day of an event, and to determine whether a threshold has been exceeded, the actual health risk can be estimated and it is therefore possible to decide whether or not an event can go ahead or whether the official bathing location should be closed.