Sewage is being tested for coronavirus in England in a bid to get a "head start" on where local outbreaks will happen next.
Sampling waste water for fragments of the virus is being trialled at 44 sewage treatment works across England - which cover 25% of the population.
And Environment Secretary George Eustice claimed it might show "where new outbreaks are likely to occur".
Data gathered by the testing is being used to refine the approach and feed into work of the Joint Biosecurity Centre (JBC), officials said.
The World Health Organisation has said there is currently no evidence that coronavirus has been transmitted through sewerage systems.
But tests are able to detect the genetic residues of Sars-Cov-2, the virus that causes Covid-19, in wastewater and those infected are thought to shed the virus in their faeces.
These genetic residues could be used to detect the presence of the virus in the population, including among those who do not have symptoms or before they develop them.
Scientists believe nationwide monitoring of sewerage systems could be a good way to identify future disease hotspots.
Environment Secretary George Eustice said: "We are working closely with researchers, water companies and devolved Governments in Scotland, Wales and Northern Ireland to monitor for fragments of coronavirus genetic material in waste water.
"The aim of this new research is to give us a head start on where new outbreaks are likely to occur.
"Sampling has started across the country to further test the effectiveness of this new science.
"Research remains at an early stage and we are still refining our methods."
The Government and Devolved Administration partners are working with academics, UK Research and Innovation, the Natural Environment Research Council and water companies in developing and testing the approach.
Testing allows the government to investigate whether the technique is useful in assessing the progress of the disease at a population level.
