Development and validation of a same-day monitoring method for recreational water

Children playing in a lake Every year, thousands of Americans take trips to recreational beaches to splash or swim in the water. When water is polluted, swimmers can become ill from exposure to waterborne pathogens. Culture-based laboratory methods, however, require 24 hours to culture bacterial indicators and determine whether water is safe for swimming. To reduce the number of swimming-related illnesses, beach managers need quicker ways to determine when beaches are unsafe for swimming and should be closed.

EPA scientists have developed a new rapid molecular-based method for quantifying fecal indicator bacteria. The new method uses quantitative polymerase chain reaction (qPCR) technology to extract and quantify DNA from fecal indicator bacteria enterococcus in water samples. This new method produces results in less than four hours rather than the 24 hours required by culture-based methods, so beach managers will be able to alert beach-goers to unsafe levels of microbial contamination before it's too late.

The qPCR method has been tested in numerous EPA epidemiological studies at freshwater and marine beaches to determine whether a consistent relationship exists between rates of swimming-related illness and water quality data produced by the method. These epidemiological studies and research on the performance of the method have found that qPCR is a reliable means for detecting fecal indicator bacteria in recreational waters.

This science will provide a foundation for the development of new qPCR beach monitoring criteria for enterococcus. Use of the new laboratory method will also result in earlier public notification of health hazards at beaches and a potential reduction in the number of swimming-related illnesses due to exposure to waterborne pathogens.