According to the outcome of the Virobathe research, in almost 40% of more than 1,400 bathing water samples collected from coastal and inland areas in nine European countries, there were viruses discovered. While the concentrations are low, the research suggested that the presence of infectious adenoviruses and noroviruses in water samples could pose a risk to health.

The Virobathe ('Methods for the concentration and detection of adenoviruses and noroviruses in European bathing waters with reference to the revision of the bathing water directive 76/160/EC') project, which was supported under the Research for Policy Support Cross-cutting activity of the EU's Sixth Framework Programme (FP6) to the tune of €2.25 million, found that around 25% of microorganisms in a small number of samples had infectious capacity.

The annual bathing water report presented by the European Commission and the European Environment Agency in summer of 2010 showed that 96% of coastal bathing areas and 90% of bathing sites in rivers and lakes complied with minimum standards in 2009. However, the research brought together 16 research organisations from Germany, Spain, France, Italy, Cyprus, Poland, Portugal, the Netherlands and the United Kingdom, evaluated the presence of adenoviruses (viruses with deoxyribonucleic acid (DNA)) and noroviruses (which have ribonucleic acid (RNA) and cause gastroenteritis) in 1,410 samples of swimming water, both freshwater and seawater. While the concentrations are low, the researchers consider that monitoring of the microorganisms is needed, particularly at times when their numbers grow such as after a period of heavy rainfall.

The European Bathing Water Directive states a limit for bacteria, but there is no particular limit for viruses. The regulation only recommends that scientific investigations be performed to determine reference parameters and reliable detection methods. According to the researchers, the outcome of this investigation shows a reliable technique that can be easily standardised (quantitative PCR) for detecting and quantifying viruses in bathing waters, which makes it possible to estimate the faecal contamination and quality of water. Aside from this there is no clear correlation between the levels of bacterial indicators cited in the regulation and the presence of the viruses studied.