Legionella bacteria, which causes Legionnaires' disease, has been found in a secondary school water system in Ramsgate.
The bacteria was found in a small area of the water system on the lower school site of Royal Harbour Academy on Newlands Lane.
Head teacher Simon Pullen said the bacteria was discovered during regular checks, and has since been dealt with.
He said: "Regular checks did pick up an element of it in one small area on the lower school.
"That was then isolated and has since been flushed through the system and we're confident it is now clear.
"They are now running further checks to ensure it is gone but we have kept that area isolated.
"No one is exposed to it as it is in one very small area which has been isolated."
The bacteria can be found in both potable and non potable water and can cause Legionnaires' disease - a severe and sometimes lethal form of pneumonia.