Like many Asian countries, the population of Hong Kong has grown rapidly after the World War II. The continuous growth of Hong Kong has resulted in dramatic increases in economic activities and sewage generated.

About 93% of the population are now served by the public sewerage system. This system includes a sewerage network of about 1,700 kilometres in total length and around 300 sewage pumping stations and treatment facilities collecting and treating 2.8 million cubic metres of sewage (enough to fill up 1,120 standard size swimming pools) per day from residential, commercial and industrial premises in the territory prior to disposal to the sea for dilution and dispersion through submarine outfalls.

In the past, whilst new towns in the New Territories have been provided with modern secondary sewage treatment works, the sewage infrastructure for the older urban areas has not been upgraded to cater for the level of development of Hong Kong. In order to cope with the development and the rise in people's standard of living, the sewage infrastructure is now being upgraded under a territory-wide sewerage rehabilitation and improvement programme.

The Harbour Area Treatment Scheme (HATS) project is aimed at improving the water quality of Victoria Harbour and is being implemented in stages. Under HATS Stage 1, sewage generated from Kowloon and northeastern part of Hong Kong Island is transferred by a deep tunnel system to a centralized treatment works at Stonecutters Island for chemical treatment before discharged into the western approaches of the Victoria Harbour. HATS Stage 1 was commissioned in December 2001.  For HATS Stage 2, it is divided into Stage 2A and 2B – the former aims to transfer the sewage generated from the northern and southwestern part of Hong Kong Island by a deep tunnel system to Stonecutters Island sewage treatment works for centralized treatment before discharging into the harbour; the latter stage aims to add biological treatment to the effluent to further improve its quality.

In the Sewerage Master Plans (SMPs), the whole territory was divided into 16 catchment areas and the sewerage network and sewage treatment facilities are being upgraded on a catchment by catchment basis in order to improve the performance of the whole system. Some older sewage treatment works will be upgraded.

The Government is continuing to invest considerable resources in the sewerage infrastructure in order to improve the environment. Over $20 billion have been committed in HATS Stage 2A and the sewerage rehabilitation and improvement programme, and more will be spent on further stages of these projects. We shall continue our efforts in combating water pollution in order to provide our community with a safe and healthy environment.