Lake Heights Public School was targeted by copper pipe thieves during the school holidays, joining two other Illawarra schools that fell victim to similar crimes this week.
Lengths of copper pipe were stolen from the school's main building early on Friday, January 24.
Lake Illawarra police inspector Paul Allman said police estimated the thieves had caused damage worth $3000, including the value of the pipes.
A Department of Education spokesman said the pipes had been replaced.
Copper pipe was also stolen from Coledale Public School last Tuesday, rendering the school's amenities block unusable and forcing children to use toilets at the nearby surf club for two days. The toilets were operational again yesterday morning.
An unsuccessful attempt to steal copper pipe from Scarborough Public School was also made on Tuesday night.
Police are investigating all incidents.
Lake Heights P&C president Tracy Beohm said the school's staff were affected by the theft, having to use a toilet in another part of the school.
She said the school last year petitioned the government to install security fencing around the grounds, but was unsuccessful.
"We're one of the few schools that don't have that high fence.
"We have surveillance cameras, so hopefully that will help, but it doesn't stop it from happening."
Coledale and Scarborough have partial security fencing.
Police are reviewing CCTV footage from Lake Heights and encouraged anyone with information about the thefts to contact them.
Insp Allman said while he was unaware of any other copper thefts at schools over the holidays, copper had recently been stolen from building sites in the region.
John Ward from Ward's Metals said copper pipe was worth between $3 and $5.50 a kilogram.