Teachers are being forced to share toilet facilities with pupils in growing numbers of schools, it emerged today.

The NASUWT said the situation in new school buildings was compromising the dignity of staff and pupils, and leaving teachers vulnerable to accusations of inappropriate behaviour.

One female delegate told the union’s annual conference in Birmingham that she had unwittingly walked into an unlocked cubicle where a teenage boy was using the toilet.

Wayne Broom, a teacher from Middlesbrough, said: “There are some schools around the country where staff and pupils have to use the same toilets, queuing up with pupils waiting for the next available toilet.

“In this day and age what problems and accusations could this lead to from pupils? We need to protect the child and the staff.”

The union says that many new school buildings exploit a loophole in workplace health and safety legislation that demand separate toilets, by just providing shared disabled facilities.

Antoinette Mutton, a supply teacher from Essex, said she was coming across “more and more” schools where staff and student toilet facilities were shared.

She told of being in a hurry in a school building where the designated staff toilet was a disabled toilet.

“Imagine my horror when I opened the door and there was a year 11 boy, luckily with his back to me, standing using the toilet,” she told delegates.

“Once my brain had started to function properly I began to appreciate the enormity of what had just happened and I went on to report the incident to as many senior staff as I could.

“I didn’t want to be accused of keeping it quiet... that could have been the end of my career.”

Department for Education guidance on school building standards published in May 2013 says that to meet regulations, suitable toilet and washing facilities must be “provided for the sole use of pupils”.

But it adds “where separate facilities are provided for pupils who are disabled, they may also be used by other pupils, staff, supply staff, volunteers and visitors, whether or not they are disabled”.

Jackie Scannell, a teacher from South Essex, told the conference:  “We have legislation that states there should be separate toilets...but that is being got round by having the facilities for the disabled which can be used by both staff and children.

“In lots of new buildings they are the only toilets that are being put in. We don’t have a choice in many buildings to be able to use separate toilet facilities. We should have.”

Delegates also heard that teachers’ and pupils’ dignity was being compromised with toilets with “glass fronted walls”.

Mr Broom added: “Currently the regulations don’t even include the supplying of toilet paper or soap. For girls and women, particularly during the menstrual cycle, not having adequate toilet facilities can cause very serious illness.

“Health is being put at risk to cut red tape, which we all know means cut backs on spending and in this case cut backs on spending a penny.”

The NASUWT national executive member said toilets were part of a wider problem resulting from the government’s decision to cut back school building regulations from 30 pages of rules to just three.

Requirements on school canteens, pupil lockers, size of classrooms, staffrooms, and maximum and minimum temperatures had all been removed, he said.