Bacteria which cause Legionnaire's disease have been found throughout Hong Kong's brand new, £432 million ($670 million) government headquarters.
The checks were prompted after the education secretary came down with the potentially fatal illness last month.
Health authorities said water samples taken from his new office's washroom found traces of legionella bacteria as high as 14 times above acceptable levels.
Authorities said nine out of more than 31 water samples were contaminated, and they are now disinfecting the building.
Early signs of the disease can include high fever, chills and a cough.
The bacteria thrive in warm water. Last year, they were found in the Playboy Mansion grotto in Los Angeles after scores of people who attended a fundraising event fell ill.