Ministry of Education figures show parents and communities contributed $712.8 million to their children's schools in donations and revenue last year, as reported by the Otago Daily Times on Saturday.
The figure included locally raised funds, investment income, and fees from international pupils.
Dunedin's Kaikorai Valley College was revealed to have received $1.1 million and Logan Park High School $1.2 million in such funding.
However, Logan Park principal Jane Johnson said the money largely came from its international pupils.
The school depended "very heavily" on international pupil income in order to be able to compete with schools which had sufficient income from other sources, she said.
"I can't imagine trying to survive without it."
Luckily, the school was popular with international pupils because it offered Latin, a course important to German education, she said.
Numbers varied but the school often had between 35 and 45 pupils enrolled from various countries, including Italy, France and Scandinavia.
The school kept a close eye on the exchange rate and it promoted itself via a company overseas.
Ms Johnson said the Government knew some schools survived solely because of these fees and believed schools would find operating easier if the state system was not "undermined" by Aspire Scholarships.
These recently introduced scholarships offered pupils from lower income families the opportunity to attend private schools.
While this scheme received funding, "we are taking cuts with ACE [adult and community education], environmental education and staffing", she said.
The school's website stated international fees for 2010-11 were $22,680, which included tuition and homestay for four terms.
Ms Johnson said 10%-15% of that went to the Government.
"There is not a lot of profit left, but we are very grateful that we can expand in that way. The students add so much to the school."
As well as funds from international pupils, the school had a range of different investments, charged fees for extracurricular activities such as sports, and was "very assiduous" in applying to charitable trusts.
"We work very hard at all of these things so that we can remain competitive," Ms Johnson said.
Otago Secondary Principals Association chairman and Kaikorai Valley College principal Philip Craigie believed the ministry's figures were misleading because "the data shows you the ins but it doesn't show you the outs".
He agreed some schools, including his, relied on international pupil fees, but described it as a service as having the pupils in Dunedin benefited the community through diversity and tourism dollars.
Schools also had to spend on supplying such pupils with teachers and materials so the venture was not simply a money-making exercise.
Kaikorai Valley had about 50 international pupils a year, with fees for 2009-10 set at $22,150.
Without them the school would be "struggling more than we are struggling", Mr Craigie said.
Any profit made from their fees went back to the school.
Supplying extra teachers was a priority.
