Secretary for Environment, Transport & Works Dr Sarah Liao says the Water Supplies Department has been drawing water to water treatment works from reservoirs which are nearing capacity to reduce overflow.

Dr Liao today told lawmakers owing to heavy rainfall this year, the amount of overflow from reservoirs reached 109.4 million cubic metres at the end of November.

The department has studied the feasibility of increasing reservoirs' storage capacity to reduce the amount of overflow, but found it is not cost-effective. It would incur project and operation costs which are higher than those of increasing water supply through other means such desalination or buying Dongjiang water.

Increasing capacity would also have impacts on the countryside and the ecological environment, Dr Liao added.