Covid: Don't turn your nose up at using waste water as way of tracking coronavirus outbreaks

Tom Clarke

Former Science Editor

I’m watching a river of raw sewage surge past our camera.

This wastewater treatment works outside Bolton serves nearly 500,000 people. And we’re filming on a warm day. Put it this way, I’ve had more glamorous assignments in my TV news career.

But using waste water as a tool for tracking disease outbreaks isn’t something to turn your nose up at.

  • Watch Go Pro footage of a waste water sample being collected

Nothing is going to replace the accuracy of an individual PCR test for Covid-19 anytime soon.

But with cases still relatively low across the country and new and emerging variants of the virus a constant concern, our sewage could become a powerful early warning system.

After all, each of us produces a “sample” more or less every day.

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Studies have shown people start excreting the SARS-CoV-2 virus in their poo up to three days before they develop symptoms of Covid.

And while the virus breaks down into harmless genetic fragments once it leaves our body, these can be reassembled using molecular techniques to spot one case of Covid out of a mixture of 10,000 individuals’ sewage.

Working with water companies, the UK Joint Biosecurity Centre says it now has a network of 500 sampling locations across England and they’re routinely testing the sewage of 70% of the population.

  • Mark Garth, Director of Wastewater Treatment at United Utilities, explains how waste water sampling works

Following an outbreak of the South African variant of Covid in Bristol earlier this year, sewage surveillance was used to demonstrate the outbreak was over.

  • Dr Johanna Hutchinson, UK Health Security Agency, says health officials were able to monitor the rise of the South African variant in Bristol

Given the delta variant is now widespread in the UK, sewage surveillance won’t teach us much about where the virus is, but it could help identify a rise in cases in an area, or a part of the population which might be missed by PCR testing.

It could also be used to look for increasing levels of a new variant — the “Delta plus” variant for example — which is now being monitored by public health officials worldwide.

  • 'Everyone takes a poo, right?': Professor Steve Paterson, from the University of Liverpool, on the benefits of using waste water