A top drainage service official said it is “unavoidable” that flooding hit parts of Sai Kung and Tseung Kwan O on Monday as heavy rain caused debris such as tree branches to block the sewer.

Acting Director of Drainage Services, Chui Si-kay, said the department received eight reports of flooding – seven of them from those two areas – with waters reaching one metre high in some spots.

“The rainfall in Tseung Kwan O is 100 millimetres per hour, which is much bigger than the Black Rainstorm which is 70 millimetres per hour,” he told reporters.

“The flooding is mainly due to the washing away of sands, leaves and debris from the land area into our drainage system, which caused blockage.”

Chui said he doesn't believe what happened on Monday had to do with the rainstorm last week, which triggered widespread flooding in Hong Kong.

“After the severe rainstorm last Saturday and Sunday, the Drainage Services Department has already deployed over 70 emergency teams to carry out inspection and desilting. We are gradually clearing all the blockage from our drainage system, so the flooding should have nothing to do with the rainfall last week.”

Chui said the situation in Sai Kung and Tseung Kwan O has mostly been dealt with, adding that workers will continue to inspect the city’s drainage system to ensure that it is in good shape.

Meanwhile, 10 schools called off in-person classes on Monday because of damage to their campuses after last week's rainstorm, and the Education Bureau said face-to-face learning will remain suspended at five schools on Tuesday.