As the country continues to ease social restrictions, and more and more people are moving about the country, raw sewage is set to become an important new front in the fight to prevent a resurgence of Covid-19.

This is particularly so in the greater Dublin area where a team of researchers at UCD's School of Microbiology are already analysing samples of wastewater from treatment plants in Enniskerry, Shanganagh and Ringsend twice a week.

They are tracking how much genetic material from the virus they can find in Dublin's sewage.

If they find that the quantity of 'RNA' from Covid-19 in their sewage samples starts to go up, it will give them a really good early indication that the disease is on the rise again in the Dublin region.

All the data and information collected will be passed on immediately to the Department of Health and the HSE. It is a new low-cost early warning system that could ultimately save lives.

Analysis of urban wastewater to help monitor and prevent the spread of disease has been used for decades to detect the polio virus in countries where that disease is still endemic.

It has also been used to detect levels of illegal drug use in certain communities in the United States.

Now it is being used to keep track of the most devastating pandemic for over 100 years in several European countries, including Ireland.

Wim Meijer, Professor of Microbiology at UCD, who is leading the project, said one of the main challenges with Covid-19 is to find out how many people in a community are infected.

"One way to find out is to look at sewage," he said.

"When people are infected they will shed the virus in their stool. When you go to the toilet eventually your stool will find its way into the sewerage system and that finds its way to the sewage treatment plant."

Professor Meijer said the amount of the virus present in sewage is an indicator of the prevalence of the virus in the larger community and measuring it can give a good indication of just how many people are infected in any region.

He referred to what he calls "a very nice study" done in Paris where, after scientists looked at the prevalence of the virus in sewage, they were able to show that the increase in the virus in sewage preceded the detection of the virus in the population through testing.

Another study done in the Netherlands showed that the virus was detectable in sewage when the confirmed detection rate was no higher than one case in 100,000 people. So it is a highly sensitive method of detection.

Professor Meijer and his team are particularly interested to see what will be revealed in the sewage from the Ringsend wastewater treatment plant in Dublin.

Ringsend serves the entire greater Dublin area, so by monitoring the incoming sewage, he said they will get a good impression of the prevalence of the virus in the Dublin community.

In terms of the science, the Covid-19 sewage project is interdisciplinary, requiring expertise from microbiology, to environmental microbiology, to molecular biology.

Professor Meijer lists colleagues in UCD's veterinary college such as Nicola Fletcher, an expert in virology, and John O'Sullivan, an expert in civil engineering, who are also making key contributions.

Local authorities, including Dublin City Council and Dun Laoghaire-Rathdown County Council, are collaborating too, as is Irish Water, which is providing the sewage samples to the researchers twice a week.

The scientists also want to find out what happens to the virus when it gets into the environment, including sewage-contaminated water bodies, rivers, stream and even the sea.

They want to know if it remains infectious, if it remains detectable, and how long does it take before traces of the virus disappear.