Under the Water Pollution Control Ordinance (WPCO), the waters of the Hong Kong Special Administrative Region (HKSAR) are divided into ten different water control zones, namely Tolo Harbour & Channel, Southern, Port Shelter, Junk Bay, Deep Bay, Mirs Bay, North Western, Western Buffer, Eastern Buffer and Victoria Harbour (Phase 1, 2 and 3). Additional waters (south Po Toi, Lantau Channel, and the waters off Tai O and the western coast of Lantau Island) were added more recently following the establishment of the HKSAR. The WPCO is now in force in all waters of the HKSAR.
The Environmental Protection Department (EPD) is responsible for enforcing controls in water control zones to achieve and maintain defined water quality objectives. Control is exercised mainly through a licensing system. Each discharge licence specifies the conditions for making the discharge, including quantitative standards to be met. Other enforcement activities include making inspections and surveys of premises, handling complaints and instituting prosecutions. Mandatory sewer connections in some previously unsewered areas are being implemented under the Water Pollution Control (Sewerage) Regulation, a programme that has been in place since late 1995. Under the Regulation, the EPD may require the owners of premises to carry out works to convey wastewater from their premises to the public sewer when it is available.