DSD is responsible for flood protection, and collection and treatment of sewage in Hong Kong. On flood protection, the major activities include the planning and implementation of the drainage systems under each Drainage Master Plan, the river channel management in the New Territories, and the operation of flood protection facilities. On sewage collection and treatment, DSD designs, constructs, operates, and maintains sewerage system and sewage treatment plant with respect to the Sewerage Master Plan prepared by the Environmental Protection Department.

Flood Protection

With an annual average rainfall exceeding 2,200 mm, one of the highest among the cities in the Pacific Rim, flooding is a serious concern in the low-lying areas of the northern New Territories and the old urban areas. DSD is tasked to reduce the risk of flooding and has been implementing a massive flood prevention programme. It includes the development of drainage tunnel, the training of river, the provision of village flood protection scheme, and the undertaking of urban drainage improvement works. To ensure that stormwater finds its way into the sea without causing flooding, DSD carried out maintenance works on 2,502 km of drainage channels and stormwater drains, and 27 village flood protection schemes in 2007. In addition to flood protection, DSD also helps prevent water pollution to the drainage systems and water bodies by providing and maintaining dry weather flow interceptors; and under emergency situation to clean up chemical spills in drainage systems.

Dry weather flow interceptor at Kai Tak nullah for diverting polluted flow to foul sewer.

Clean up of traffic accident spills in Ho Chung River

Sewage Collection and Treatment

DSD collected and treated 960 million cubic metres of sewage in 2007. The facilities for handling the sewage include 69 sewage treatment works (STW), 209 sewage pumping stations, 44 submarine outfalls, 3 effluent disposal tunnels, and 1,546 kilometres of sewers.

Following the successful commissioning of the pilot scale tertiary sewage treatment plant at Ngong Ping in 2006 for effluent reuse, DSD continues her effort in supporting trial work in total water management. In 2007, we worked with the Environmental Protection Department on another pilot scale effluent reuse project in the North District. The tertiarily treated effluent from a pilot plant in the Shek Wu Hui Sewage Treatment Works was supplied to a residential area, one elderly centre, and three schools for toilet flushing purpose.

Pilot Plant for Effluent Reuse in Shek Wu Hui