Holy water: not as clean as hoped

Furtwangen University study compares contamination in churches

Is holy water more dangerous than useful? What is the result when large numbers of people dip their fingers in the font? These questions were behind a recent scientific experiment. Although holy water is a standard feature in Catholic churches, until now it has received little attention from scientists. A team of students and researchers from the “Molecular and Technical Medicine” study programme at Furtwangen University recently looked at this question by comparing 54 holy water samples from 5 churches in Villingen-Schwenningen and the surrounding area.

The first study carried out in Germany on the topic of microbial contamination of holy water has now been published in the "Journal of Water and Health" (https://doi.org/10.2166/wh.2017.026). The study with the title “Quantification and identification of aerobic bacteria in holy water samples from a German environment” was authored by Christoph König, Stephanie Tauchnitz, Heike Kunzelmann, Christian Horn, Frithjof Blessing, Matthias Kohl and Markus Egert.

Three town churches and two village churches were sampled several times. On average approximately 6,000 microbes per milliliter were measured. The holy water from town churches with between 1,500 and 21,000 microbes per milliliter was significantly more contaminated than the village churches, which had levels of only around 100 microbes per milliliter. “We assume that this large difference is caused by the higher number of visitors in the town churches,” said Prof. Dr. Markus Egert, who led the study. “The number of germs shows a correlation with the size of the community.”

In Germany there are almost 24 million Catholics of whom a good 10%, about 2.5 million, regularly attend mass. The topic of holy water is somewhat tabu. “Even so, with the increasingly aging congregations in mind, we wanted to investigate this topic,” said Egert. “The local church representatives were very open to our experiment.”

Besides water bacteria, the researchers mainly found bacteria of the human skin flora, particularly staphylococcae. Fifty percent of the isolates identified were potential pathogens. Staphylococcae are a well-known cause of skin and soft tissue infections, for instance abscesses. In total, 20 different types of bacteria could be positively identified.

The researchers recommend taking hygiene measures in order to prevent the microbial contamination of the holy water. This should take the form of regular changing of the water, particularly in churches where there are large numbers of visitors. “The ritual adding of salt to the holy water does add an element of conservation,” explained Professor Egert. “However  Staphylococcae especially are well-known for their tolerance to salt.” The researchers want to do further follow-up work in the area of microbe growth reduction in holy water fonts. One of the approaches used will be the material used in the font. Better conditions may be achieved by using metals such as copper.

One piece of good news however: the number of germs found in the samples from the Villingen-Schwenningen  area were up to 1000 times lower than the values from an Austrian study (Kirschner et al., 2012) which compared churches in Vienna. Even if the water in the fonts is no longer drinking water quality, there is still no danger when it is used externally on undamaged skin.