A killer disease is lurking inside one in every three train toilets, a shock study has revealed.
Scientists found deadly Legionella bacteria during emergency checks on hundreds of carriages earlier this year.
All rail companies serving Sussex – Southern, First Capital Connect and Southeastern – confirmed their trains were tested.
However, all three refused to reveal how many of their toilet tanks were found harbouring the bug.
Infection with Legionnaires’ is caused by breathing in small droplets of contaminated water – and can be fatal.
The rail companies insist health risks to the public remain low but passenger groups have called for swift action.
The deadly bacteria was first discovered in two Virgin train toilets in Scotland in February 2011.
Later that year, an outbreak in Edinburgh killed three people although none of the cases were known to have been contracted on a train.
However, worried rail bosses ordered an emergency report to assess the scale of the problem.
Out of around 300 toilets tested, around 30% tested positive for the disease.
As soon as infected carriages were discovered, they were scrubbed and chlorinated to kill the bacteria.
Further changes, including updating toilet tanks, will now be made to protect passengers.
Shelley Atlas, of campaign group Brighton Line Commuters, said the discovery of Legionella in train toilets was “concerning”.
She said: “I’m sure this news will be extremely worrying for many passengers.
“The responsibility now lies with the train companies to make sure everything possible is done to make sure no one comes to harm.
“With an issue as important as this, they need to be as transparent as possible.”
A spokesman for the Association of Train Operating Companies said: “The new report, commissioned by train companies, supports what the Health Protection Agency has already confirmed which is that the risk to either passengers or to the general population is extremely low.
“Operators will continue taking appropriate action to deal with the issue, including, but not limited to, disinfecting water tanks.”
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