The Rotorua Aquatic Centre has been forced to close after an issue with the bore that provides heating to the pools was discovered.
Rotorua Lakes Council said an investigation following a loss of heat to the outdoor pool yesterday found geothermal sediment in the bore pipes, which can cause blockages and damage.
This meant the bore had to be shut down to enable further investigation of the cause and to determine what steps need to be taken to fix the problem.
Swim clubs were being notified and the centre would need to remain closed until further notice, the council said.
Under the Building Code, the centre could not remain open without a domestic hot water supply.
The council and contractors would be working to identify and rectify the bore issue as quickly as possible so that the facility could be re-opened.
The centre, which was managed by CLM, is currently undergoing a major upgrade, with just the outdoor facilities open while construction was under way.