I have been much exercised recently by toilets and by the huge prominence they assume during the school day. They have been flooded again, you see. The pans have been blocked with paper and the sink wastes pulled off. It’s a mess.

As always, I feel guilty that I have to ask the caretaker to clean them up, as if in some way I have failed again to control the forces of unreason. But as I tell him, they have to be open and they must have paper, even though we all know it will happen again soon. For the caretaker they are a nightmare, no question - a festering and viperous den into which he must venture alone, armed only with a brush. Make no mistake about it. Toilets are dangerous places.

They squat there within the building, fragrant and brooding, with the power to ruin an individual lesson or a whole day. They are the dark heart of anarchy, a territory that is impossible to subdue, a place of tribal loyalties, shifting alliances, arbitrary acts of unreasoning terrorism. They are our own little Afghanistan.

For all teachers, the toilets are an issue fraught with difficulties. You have to make difficult and instant decisions. Even if we’ve done the job a long time, we still find it difficult to distinguish between those who have an urgent appointment and those who just fancy a walk. And what happens when you let Jade go? Can you refuse Craig? Or Donna? Do they all go? Or does no one ever go? Whatever policy you try to enforce, you are always a hair’s-breadth away from chaos the moment Dean raises his hand. How is it possible to operate a system with no grey areas? Is there any other basis on which to make a decision other than instinct?

Of course, even the sort of public performance in the classroom that pupils often threaten might be preferable to braving the toilets. For it is there that western civilisation dissolves into barbarism.

Toilets are places in which anyone can be stripped of their dignity. You have to be truly desperate to run that gauntlet, to shut yourself into a cubicle that probably has no lock, at a moment when you are most vulnerable. And then you will find there is no paper. It has all been stuffed down the pan or stuck to the ceiling. It is no wonder that some of the boys prefer to frequent the fence at the edge of the playing fields.

In my school the girls are, by far, the worst. They hide in there, they smoke, they eat their dinner. They regard it as their haven, their space and their refuge. There is a genuine sense of intimidation for anyone who enters, whatever their purpose.

The problem is not peculiar to schools here, though. I have just finished marking exams from around the world. In their papers, students in Botswana complained about graffiti and a lack of respect for the facilities they share. In Singapore, the toilets are a place where the girls hide when they are dropped from the volleyball team. It seems they are viewed universally as a place apart, a place where a different authority holds sway. It is in the toilets that you can strike back against the system. They are a staffroom for the disaffected.

You can wreck the toilets as a sign of defiance, a triumph of the spirit over the grim ogres of oppression. But there is no doubt about their function as a refuge. They are a place where you can express your anger, where your burning sense of injustice can take shape among the blocked sinks and declarations of undying carnality, where you can, indeed, rage against the machine.

Perhaps I am locked into some sort of symbiotic relationship with the kings of the toilet. Just as it is my job to ensure that they are cared for, well stocked and comfortable - for that is what I would want for my own children - so it is their duty to turn them upside down. How else are you going to show that you are not an individual to be trifled with, before you disappear forever into the anonymous employment of the telephone call centre?

School toilets must be disgusting. That is their purpose. It is their destiny. It is my job as a responsible adult to protect them and, during assembly, to threaten vile retribution to the culprits . It is their duty to outwit me.

Let battle commence.

Geoff Brookes is deputy head of a Swansea comprehensive.