Fresh water and sea water are supplied through two entirely separate systems of pumping stations, service reservoirs and water mains. The water is pumped and, in some cases it flows by gravity, after leaving the treatment works or being extracted from the sea to the service reservoirs which are located at various places and elevations throughout the territory, each serving a particular area. The roof areas of the service reservoirs situated at convenient locations are generally developed by the Leisure and Cultural Services Department for recreational purposes.

Click to view a Typical Fresh Water Supply System.

Water from the service reservoirs is distributed to customers by gravity via extensive networks of water mains. The pressure in the system is generally sufficient to provide a direct supply to six or seven storeys above street level. Upper floors of tall buildings are supplied from their own roof tanks, filled by their own pumping systems. For higher level areas, such as mid-level developments on Hong Kong Island, it is necessary for the water to be pumped in stages to service reservoirs situated at different suitable levels. For remote village areas, the pressure in distribution network system is normally sufficient to provide a direct supply to three storeys above ground level.

The distribution system serves to transfer water from one location to another by means of mechanical pumping or by gravity. Most of the pumping equipment is electrically powered and the Water Supplies Department is one of the largest consumers of electricity in Hong Kong.

The department has used modern supervisor control and data acquisition system (SCADA system) to improve the centralised monitoring and control of the various processes of water distribution. This system links up the real-time data of the various installations and provides data for effective means of on-line monitoring and control.