Te Tai Tokerau Principals' Association president Pat Newman suspects that methamphetamine is now harming children in every classroom in Northland.
"Rampant" use of the drug in the North was affecting so many families it had become a major concern at schools, and he doubted that there was a class in Northland that did not have a child who was somehow affected by it.
"That could be, at the very worst, living in a house where it is manufactured and breathing in the fumes, through to parents using the money for [drugs] that should be on food, to seeing violence that goes with P," Mr Newman told Newstalk ZB's Early Edition.
"I think it's the community that needs to say, 'Look, we own this problem'."
Mr Newman made his comments in the wake of two primary school-aged children reportedly being caught taking methamphetamine to school, although he had not heard of these incidents.
"The authorities will tell you it is probably easier to get your hands on P than it is on marijuana in the North," he added however.
The prevalence of methamphetamine was also highlighted in a report published this week in the Royal Society of New Zealand's social sciences journal Kotuitui. It looked at 578 children affected by their parents' drug use, finding that substance abuse was the most common reason for children living with their grandparents.
Such had "often sporadic and unsatisfactory" contact with their parents, many of whom had died, gone to prison or moved away. Fourteen per cent of grandparents said one or more of the children in their care had assaulted them physically.
"In most cases the child appeared to lose control of their responses," the report said.
Mr Newman said that as more children came to school affected by the drug, teachers were encountering "all sorts of behaviours," usually developmental delay to the point where a 5-year-old was not ready to go into a classroom.
Northland schools and agencies were used to getting very little help to combat drug use, and ultimately the community had to take responsibility for the issue, including by reporting meth use.
"We've had children removed from homes because of P use in the home, and I think it's the community that needs to say, 'Look, we own this problem'," he said.
"It is too big for schools to do it on their own, it's too big for agencies to do it on their own, it has to be the community that turns around and says enough is enough."