Lack of money must not be used as an excuse for failing to improve the state of school toilets in Wales, according to the children's commissioner.
In his annual report, published last week, Keith Towler said he was still concerned about substandard, unhygienic toilet facilities for pupils, despite repeatedly raising the issue during his tenure.
He said: "I continue to hear from children about their poor experiences of school toilet provision. I also hear from parents that the first thing that their children do when they return from school is to go straight to the toilet.
"Best practice can only be secured through schools, governing bodies and local councils taking seriously the concerns of children and working with them to find long-term solutions to this basic issue.
"I don't want see the difficult current financial situation being used as an excuse not to respond to this priority."
Mr Towler said he conducted research in schools last year and found that only a third of pupils felt their school toilets were always clean.
Only a third said soap and hot water were always available, and only 40 per cent said soft toilet paper was always or mostly available.
More than half of the children reported that their toilet doors did not close or lock and almost half did not have seats on their toilets.
Mr Towler said: "I urge all adults concerned with the organisation, running, maintenance and overview of schools to ensure that their toilet facilities for their pupils are the best that they can be. We as adults owe this to children as they have the right to the highest standard of health."
A damning report first attacked the state of Wales's school toilet facilities in 2004. Lifting the Lid, by the former children's commissioner the late Peter Clarke, raised serious concerns about the impact of substandard toilets on health and well-being.
In September, the Welsh Government is due to publish a guidance document aimed at local authorities, governing bodies and headteachers to help them to improve standards.
A Welsh Government spokesman said: "Responsibility for the provision of adequate school toilet facilities rests wholly with local authorities. We are, however, aware of concerns and recently consulted on our draft guidance on how best to improve school toilet standards. We are now considering the responses we received."
The guidance will be published in September.
The commissioner's report also revealed a 20 per cent increase in the number of education cases reported by children and young people.
Among the issues were "special educational needs, complaints, provision and school transport," it said.
Original headline: Schools urged to spend a penny (or two) on toilets