Campaigners have called for urgent action over water companies discharging raw sewage into the sea.
It comes as swimmers told the BBC of how they saw toilet paper and baby wipes off the Kent coast.
Southern Water said the discharges are heavily diluted, typically being 95% rainwater, and done to protect homes, schools and businesses from flooding.
Pressure group SOS Whitstable demanded the water industry be renationalised to allow for more investment.
Water companies are currently allowed to discharge sewage in exceptional circumstances to prevent flooding.
Nearly fifty beaches in England and Wales were given pollution warnings in August.
SOS whitstable's Sally Burtt-Jones said: "People report they've been sick from swimming, (with) ear, eye infections, bacterial infections resulting in diarrhoea.
"Presently, the system is completely overwhelmed, and that's due to a lack of investment in the infrastructure since privatisation over 30 years ago."
Much of the UK has a combined sewerage system, with wastewater and rainwater carried in the same pipes to treatment works.
Heavy rain can overwhelm those pipes, and in such cases water companies are allowed to discharge raw sewage into rivers and the sea to protect homes.
This month the government published a plan to restrict discharges into the sea and rivers, promising "the strictest targets ever".
Rebecca Douglas said she and a friend encountered sewage in the sea off Whitstable while paddle boarding, despite checking pollution monitoring apps and websites first.
She said: "I just thought, 'Oh, my goodness, that is raw sewage there, and my feet are in there, all the boards have been in it'.
"I could see toilet paper, baby wipes, and there was just this layer on the beach."