Approval of RT-PCR to measure intestinal enterococci

Drinking water tested faster for faecal bacteria thanks to new RT-PCR measurement method

An important step for the Dutch water sector: the RT-PCR method has been officially approved by the Human Environment and Transport Inspectorate to determine the presence of intestinal enterococci in drinking water. This means that drinking water utilities and laboratories can use this faster and more sensitive method to detect these faecal indicator bacteria and thus safeguard the quality of our drinking water.

The reverse transcription polymerase chain reaction (RT-PCR) method had already received approval in 2019 for another faecal bacterium: E. coli, and is now available for intestinal enterococci (IE). The alternative measurement method is faster than the traditional culture method. The quality of the drinking water can be determined in a few hours by measuring the presence of faecal bacteria, while the traditional method could take several days.

Quicker emergency management

This faster result is a great advantage, particularly when quick reaction is needed in an emergency context. Leo Heijnen, KWR researcher: ‘The presence of faecal bacteria in drinking water can point to a faecal contamination which constitutes a hazard to public health. That’s why it’s important that the RT-PCR method can now be used for both E.coli as well as IE, so that we can make optimal use of this speed.’ RT-PCR is moreover more sensitive that the standard measurement method.

A collaborative performance

The development and approval of the RT-PCR method for IE is a result of an intensive collaboration between KWR, all Dutch drinking water laboratories (AQZ, Vitens, WLN and Het Waterlaboratorium) and the Belgian laboratories of De Watergroep and Pidpa. ‘We have been working for a number of years on the RT-PCR method within the Joint Research Programme’, says Heijnen. ‘In 2023 we concluded validation research that demonstrated that comparable results are obtained with the two methods.’ The outcomes of the different investigations have led to the approval by the Human Environment and Transport Inspectorate, which is part of the Ministry of Infrastructure and Water Management.

Image 1. Schematic representation of the research design.