Ahead of the race, scientists are urging those competing to cover any cuts and not to swallow river water - after tests revealed high levels of E.coli along the stretch of the river that will be used.
Water companies pumped raw sewage into British rivers and seas for a record 3.6million hours last year, more than double than in 2022, new figures have revealed.
Photos show sewage flowing into the River Thames at Thames Water-run Crossness sewage treatment works in east London today. Data shows it was pumped for five hours and 45 minutes.