Sewage systems could be tested for coronavirus to find new hotspots, Downing Street says

Tests could be conducted on sewage systems to identify local outbreaks of coronavirus and allow the reimposition of lockdown measures in new hotspots, Downing Street has said.

But prime minister Boris Johnson confused MPs in the House of Commons by suggesting that the tests would be carried out on water supplies.

His comment appeared to raise the prospect of water contaminated with the Covid-19 virus coming through the taps, when in fact it is waste water which scientists believe may provide a clue to the location of clusters of infections.

As he set out details of his recovery strategy for the gradual easing of lockdown measures, Mr Johnson told MPs the government would have no hesitation in “putting on the brakes and delaying or reintroducing measures locally, regionally, or nationally” if there were signs of a fresh spike of Covid cases which threatened to take the rate of reinfection - known as R - above one.

The PM - who later compared the process of suppressing localised outbreaks to the game of Whack-a-Mole - added: “The intention is the Covid alert system in time will be sufficiently sensitive and flexible as to detect local flare-ups, so that, for instance, if Covid is detected in the water supply of a certain town or in a school, in an area, then steps can be taken on the spot to deal with that flare-up.

“Measures can be taken to keep the R down locally as well as nationally."

Mr Johnson’s official spokesman later clarified that the PM had intended to refer to sewage systems.

“Some studies have been carried out overseas on this and I think it is something we are looking at as a possible way of seeing if you could track the rate of infections locally,” said the spokesman.

Officials were investigating whether sewage samples would allow them to “track if the virus is more prevalent in some parts of the country than in others”.

He added: “Obviously it is just one of a number of ways we could do that.

“To the best of my knowledge, it is something we are looking at doing rather than something we are doing already.”

Mr Johnson returned to the theme in the daily Downing Street press conference, saying: "Part of the solution is going to be, as we go forward, responding with local responses. So if there's a flare-up somewhere in the country in a particular town or village which we've detected with our Covid alert system, then we will be firefighting, playing Whack-a-Mole, to deal with that issue as it arises.

"Having a local, regional, national approach makes sense."