Could London follow Paris' Olympic efforts and make River Thames clean enough to swim?

We never meet Emma Stone’s aunt in the 2016 film La La Land. But when Stone sings that she “tumbled into the Seine” then “spent a month sneezing”, we can fairly guess the reality would be a touch worse.

Efforts to clean up the Parisian river, at a cost of £1bn since 2015, in time for the 2024 Olympic Games have hit the skids. High levels of E.Coli mean the men’s triathlon was postponed until Wednesday morning (31 July).

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For Brits watching the games, however, “nearly clean rivers” is a distant aspiration, with water companies filling our waterways with raw sewage. 

But was the French plan realistic? And could we clean up the River Thames in the same way? Experts interviewed by the Big Issue say some solutions are on the horizon – but that climate change may make it harder.

Why the River Seine isn’t clean in time for the Paris Olympics

At the heart of the grand Parisian scheme to clean up the river Seine is a giant rainwater runoff tank, which holds extra water during periods of heavy rainfall. It is intended to prevent the sewer system from getting overwhelmed and in turn stop discharges of sewage into the river.

The build up to the Olympics saw the city’s mayor, Anne Hidalgo, swimming in the river Seine – a feat illegal for the public since 1923. But rainfall, seen globally during Friday’s opening ceremony, threw a spanner in the works.

Pollution levels remained too high for triathletes to take to the water for the originally-set date. If the water quality did not improve, the event would have gone ahead a duathlon. But the missed target was not the world’s biggest shock, said Wouter Buytaert, professor in hydrology and water resources at Imperial College London.

“I am not at all surprised because it is a tremendous undertaking, and even if all sewer overflows can be fixed, then there are still many other sources of pollution, such as agricultural runoff that contains fertilizers and pesticides, road runoff with heavy metals, oil, and tyre wear, among others,” Buytaert told the Big Issue.

“I think indeed that the French were very courageous and ambitious to take up the challenge, and it was certainly worth the effort, even if the result was not entirely as they hoped.”

French action can set an example for the UK, said Charles Watson, chair and founder of River Action.

“It has cost nearly a billion pounds and nearly as much as in political capital, but it demonstrates what can be done to improve water quality when there is the will to restore healthy waterways,” Watson said.

Could we do the same with the Thames?

The Thames is not clean. Ahead of the 2024 Boat Race, rowers were told not to throw each other into the river because of high levels of E.Coli. In the first eight weeks of 2024, Thames Water pumped raw sewage into the London stretch of the Thames for an equivalent of 79 days. But there are hopes that the new Thames Tideway will clean up the capital’s river.

The 25km super sewer under the Thames, stretching from Acton to Stratford, has cost £4.5bn. It was completed in March and is set to open in the next few months. Its designers hope it willI reduce sewage flowing into the river by 95%.

“The problem is no-one will see it because the river Thames is a pretty muddy river, and it will remain muddy, so it won’t look any cleaner but it will be a lot cleaner,” Nick Raynsford, a former Labour minister who now chairs the Tideway Reporting Group, told the Big Issue.

“The next moment of truth will be next year’s Boat Race,” he added.

“Next year we will see, because by that stage Tideway should be fully operational and the discharges should have reduced.” 

Yet this solution still involves a huge volume of water needing to be treated, Buytaert added.

“A much more structural solution would be to separate the pretty clean rainwater from the much dirtier sewage flows. Doing that for all existing sewers and connections would be an awfully big and expensive job, and certainly much more than £1bn,” said Buytaert.

“A good place to start is with new building developments, which now require separation of rain and sewage.” Households could stop rainwater entering the sewage system through water butts, freeing up space for the system to deal with sewage, suggested Buytaert.

Action on the water industry is also needed, said Watson: “Here in the UK, the newly elected Labour government has promised to take on the broken water industry that has poisoned our rivers with human sewage.

“But it’s not only the water companies that should be worried. We also need urgent action to reduce pollution from industrial-scale agriculture that has, for example, caused ecological collapse on the River Wye.

Climate change is making it harder to clean up rivers

Climate change will make it harder to clean up rivers, like the Seine. Water quality globally is getting worse.

“The postponement of today’s men’s triathlon at the Paris Olympics due to poor water quality shines a light on the ‘invisible water crisis’ of global river water pollution. Water quality issues are often overlooked when compared to the visible impacts of floods and droughts,” David Hannah, professor of hydrology and UNESCO chair in water sciences at the University of Birmingham, told the Big Issue.

Water quality issues are a global and persistent problem, with a desperate need to act on pressures coming from humankind, he added.

“To move from the water pollution crisis to solutions, we need to use the latest scientific thinking and data sources; empower decision makers across different levels of governance to act; regulate more smartly; and encourage international cooperation and data and knowledge sharing between places with varied status of economic development,” said Hannah.

For the Tideway, heavy rainfall from climate change presents a challenge for cleaner rivers.

“Both the storage tank solution in Paris and the tideway here could be overwhelmed in certain circumstances of extreme storm conditions,” said Raynsford.

“That really emphasises the importance of separate action taken against climate change to avoid a further deterioration in weather patterns.”

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