Some of Auckland's most popular high schools are closing their doors to out-of-zone students, signalling the beginning of the end of 30 years of fierce competition for student enrolments.

Three schools have stopped offering places to students outside their home zones, with limited exceptions, and at least four others are reducing out-of-zone enrolments because of population growth in their home zones.

Mt Albert Grammar and Glendowie College, have stopped holding ballots this year for out-of-zone students unless they already have other family members at the schools.

Western Springs College also no longer accepts out of zone students except for those in its Māori "school within a school".

Avondale College, where more than half the roll has come from West Auckland areas outside its zone in recent years, is expected to cut out-of-zone enrolments so that it can fit in students from a new housing development of up to 4000 homes on the Unitec site over the next few years.

Mt Albert Grammar has given notice that it will redraw its zone to exclude Unitec because the school is full, leaving Avondale College as the only state secondary school that will still include the area in its home zone.

Mt Roskill Grammar, One Tree Hill College and Green Bay High School also expect to reduce out-of-zone enrolments in the next few years, and other state secondary schools on the Auckland isthmus are expected to face the same pressures from growing in-zone populations.

New infill housing and apartments are sprouting across the isthmus under the unitary plan approved by Auckland Council in 2016, which allows for 422,000 extra houses in the region over the next 25 years including 270,000 in existing built-up areas.

Mt Albert Grammar headmaster Pat Drumm said his school was also attracting more in-zone students from private and integrated schools, forcing it to end the ballot for out-of-zone students without siblings at the school.

"It was a decision made by the board last year with huge in-zone growth," he said.

"We ended up having I think 50 siblings of current students - not even siblings of former students.

"As the school grew rapidly over the last 10 years there was a significant out-of-zone enrolment up to about 20 percent. We are down to 6 or 7 percent in Year 9 this year and that will obviously decline."

"We have about 10 per cent out-of-zone, mainly from neighbouring areas around Glen Innes, Mission Bay, Meadowbank and Ellerslie," he said.

"We took significantly less out-of-zone last year, it's our lowest ever as a percentage. We don't take any category, only people who had a [family] affiliation with the school."

Ministry of Education data shows that 26 per cent of the students at primary and secondary state schools that have enrolment schemes in the six local board areas on the Auckland isthmus currently come from outside the schools' zones - a number that has increased from 10,830 in 2012 to 12,350 last year.

But the flow into the isthmus schools from west and south is expected to shrink as infill housing develops. Statistics NZ projects the isthmus's population aged 5 to 19 to grow by 18,630 over the 30 years from 2013 to 2043.

Drumm said the Education Ministry was well aware of the projections and he was frustrated that it had not funded enough classrooms or new schools to accommodate the extra students.

It has approved a new science block at Mt Albert Grammar, but is funding only 12 classrooms in it initially with plans to add four more when needed. But Drumm said all 16 were needed now.

He said he could not believe that the Government had chosen to build housing on the Unitec site without planning for a new school there.

"You have a fantastic tertiary facility there which would have been synergy with a school on the site. There was a huge opportunity to look at potentially a trades-type or technical school," he said.

But the ministry's deputy secretary Katrina Casey told the Herald last year: "Our planning does not indicate the need for a new secondary school in the Auckland isthmus. Rather we expect schools to reduce their out-of-zone enrolments first; then we will add capacity as required."

Secondary Principals Association president Mike Williams said the ministry had allowed schools like Mt Albert Grammar and Avondale College to grow to around 3000 students each by attracting many from outside their zones.

"The ministry has been complicit in supplying property [buildings] to schools that have grown to that size," he said.

"What was always intended was that schools would have a zone and would meet the needs of the local students, and that's what they would be staffed on.

"That is starting to come to fruition as the schools are filling up and they haven't got sufficient extra property so they have to limit it."

However he said most secondary schools across the wider Auckland region still had many out-of-zone students, including 25 per cent of the roll at his school Pakuranga College, and he did not know of any schools outside the isthmus that were closing out-of-zone enrolments.

"It's pretty early days to say that is going to be a generic trend," he said.

The new Labour-led Government has appointed a taskforce to review the "Tomorrow's Schools" system of self-governing schools which has allowed schools to compete for students since 1989. Education Minister Chris Hipkins has said that the benefits of competition "have run their course".

He told the Weekend Herald he still did not see a need for a new secondary school on the isthmus, although a new primary school to serve the Unitec project was possible.

"The Government can't continue to build school capacity in central Auckland schools so that they can take out-of-zone students," he said.

"The Government's vision is that every school in the country will be a great school, and that parents should have confidence in sending their children to their local school where they will get a world-class education.

"If people are anxious about some schools not accepting enrolments because of population growth, they shouldn't be."

National Party education spokeswoman Nikki Kaye said the former National Government was working on a 30-year Auckland education growth plan. Last year she suggested opening "urban schools" in leased city premises, using community facilities instead of having their own playing fields.

Kaye said she was "open-minded" about possible changes to zoning processes.