The lead in water scandal has now reached Hong Kong English Schools Foundation schools.
The ESF said testing has shown water with lead levels slightly above government guidelines at four schools.
The ESF newsletter said the four schools were King George V School in Ho Man Tin, Sha Tin College, South Island School in Aberdeen and West Island School in Pok Fu Lam. A further 300 samples were within the guidelines.
An ESF spokeswoman told Around DB today that they were still waiting for test results from Discovery College, an ESF school.
The tests were ordered after a public housing estate was found to have lead in its water in July.
The Hong Kong government follows guidelines from the World Health Organisation for drinking water, which state water should not contain more than 10 micrograms of lead per litre.
ESF said the four water sources had been shut down to ensure water quality.