Peter Thain, of Bristol, has decided to lobby the Government to end the widespread practice of banning toilet breaks during lessons to prevent disruption, because, he says, it can force pupils into embarrassing accidents.
"Children have no rights to go to the toilet or even have toilet roll and soap. If I was in a prison I would have rights, but because I am a kid at school no one seems to care," he told campaign group Bog Standard.
An estimated 96 per cent of girls and 70 per cent of boys have been refused access to the toilet, according to the most recent Youth Parliament survey.
Fifty per cent say their toilets are locked during lessons.
"I was in a double lesson and I badly needed to go to the toilet, so I said, 'Sir, I need the toilet.' He replied 'No.' 'But, Sir, I really need to go.' I was told 'No' again. I went back to my place and eventually wet myself," Peter said.
Nickie Brander, the chief organiser of Bog Standard, said she has been contacted by dozens of pupils who have suffered humiliation due to similar bans.
"The current situation is an infringement of human rights. It's a devastating thing to happen and leaves pupils open to being teased and bullied," she said.
"The body doesn't function according to a rigid timetable, and while teachers think these rules stop disruption, they mean children cannot concentrate."
The outcry coincides with the publication of Government guidelines on toilet standards, which ask schools to install clean, unisex wash areas with raised noise levels like loud ventilation systems to ensure "aural privacy". The rules are designed to improve hygiene and combat bullying.
But they only apply to schools being refurbished under the Building Schools for the Future programme.
Dr Katharine Price, a consultant paediatrician at Sheffield Children's Hospital, said that barring children from the toilet could cause health problems, including constipation. "These conditions are very common and the toilet issue does not help," she said.
Bedminster Down, a BSF school in Bristol, built a unisex toilet block which open on to a busy corridor and only has doors on its cubicles.
"There is no question it has reduced incidents of bullying," said headteacher Marius Frank.