Kingaroy and Murgon hospitals have also returned a positive result to Legionella bacteria.
Darling Downs Hospital and Health Services Chief Executive Dr Peter Bristow said no hospital wards have been closed and all facilities are operating as normal.
"Where positive results have been found we are heat disinfecting the water pipes and we will replace or disinfect taps," he said.
INITIAL STORY: 2.55PM
DISINFECTION has begun at two hospitals and outpatient facilities in the South Burnett where traces of the potentially-deadly legionella bacteria have been found.
The bacteria has been found at Wondai and Cherbourg hospitals.
The testing was sparked by the death of a Brisbane cancer patient from legionnaire's disease at the Wesley Hospital.
Darling Downs Hospital and Health Service chief executive Peter Bristow said there was no cause for alarm.
"There's very little risk to patients and past patients, we commonly treat patients for legionella," he said.
"The risk to patients is very low."