Parents will have to fork out up to $1.5 million to send their kids to one of the state's top public schools, new house price data has revealed. The analysis shows that catchment zones such as Newtown, Castle Hill and Burwood Girls have some of the lowest median house prices of the top 20, peaking at $1.37 million for Castle Hill. Former Productivity Commission economist Trevor Cobbold, who now runs public education advocacy group Save Our Schools, said high house prices entrenched the advantage of wealthy families accessing education. "It is an open question as to whether these schools are adding more value to education than lower socio-economic status comprehensive schools elsewhere or whether their higher results simply reflect their greater concentration of students from wealthier families," he said. "It is possible that spending up to $2 million to get into these schools just buys a well-off peer group rather than better results. Their children are likely to do just as well in other schools because of the advantages conveyed by the higher income and wealth of their parents."

St Marys Senior High School, which beat the HSC results of many of its higher priced peers in Turramurra, Cronulla and Killarney Heights, has a small catchment zone that recorded only 12 sales in 2016, but had the lowest median price of all the top 20 Sydney schools at $410,000. Domain, which is owned by the Herald's publisher Fairfax Media, also included median rents in their data for parents who are unable or unwilling to buy into the property market in the top performing areas. Cheltenham, Cherrybrook and Killara offered some of the cheapest median rents of between $700 and $850 a week for a house in the catchment zone of the highest performing schools. Geoff Dean from Belle Property Killara said there had been an influx of education-focused Chinese-Australian families in the area in the past decade or more.

"Chinese families really buy for the Killara High catchment zone. It certainly adds to purchase prices," he said. Mr Dean said there was a sort of virtuous circle for the schools in the area. "It's like a self-fulfilling prophecy, the people who move into the area to send their kids to school are the ones who are interested and feel education is really important. They're the kids getting pushed hard by the parents, they're the ones getting the extra coaching, and that's why the schools are getting the good results." Killara resident James Kwok moved his family to the area six years ago so his two children, now in Year 11 and 12, could attend the school.

"It seemed to have a pretty good reputation," he said. "I'm generally quite happy with the school. The kids seem to be doing quite well." He said he knew of at least one other family that had moved into the area based on the school. "Yes, it is happening more and more," he said. "That's what I keep being told by the real estate agents anyway, they keep knocking on my door and asking if I want to sell." Other buyers are looking at the long term, snapping up opportunities to secure spots in primary schools, while also keeping an eye on future high school opportunities. Catchment zones in Neutral Bay, Vaucluse and St Peters all saw house price rises of more than 26 per cent in the past year.

Chris Quevedo and his wife Lucy bought in Petersham for $1,365,000 because it was close to a combination of good public, private and Catholic schools for their four-year-old son Joshua. Loading "The ranking of the schools in the area is high and where we bought is on the border of several schools, so we'd be able to get him in if we tried," Mr Quevedo told Domain. With Inga Ting, Jennifer Duke and Toby Johnstone