Safe drinking water is vital to your health and to the continued development of Hong Kong. Here you can gain an overview of how the Water Supplies Department provides drinking water for Hong Kong, and the processes involved in safeguarding its quality.

Fresh water is limited in Hong Kong, which experienced water shortages until the 1960s when the Government began to import raw water from Dongjiang (the East River) in neighbouring Guangdong province. Currently, around 70-80% of our fresh water comes directly from Dongjiang, and 20-30% comes from local catchments. An agreement between the Hong Kong Government and the Guangdong authorities ensures the stability of the Dongjiang water supply to Hong Kong, with the water quality meeting the national standard for Type II waters (applicable for the abstraction for human consumption in first class protection area) under the "Environmental Quality Standards for Surface Water, GB 3838-2002". A series of rigorous water treatment processes in Hong Kong then ensures that the drinking water quality complies with the World Health Organization's Guidelines for Drinking-water Quality.

• More on water from Dongjiang
  http://www.wsd.gov.hk/en/html/water/dongjiang.htm

Maintaining a consistently high level of water quality requires meticulous planning, comprehensive infrastructure and logistical coordination. Over the last decade, the Government of the Hong Kong SAR has worked closely in partnership with the Guangdong authorities to protect the quality of water imported from Dongjiang. One of the most significant initiatives has been the construction and operation of a dedicated aqueduct that has isolated the sources of water pollution along the route of supply to Hong Kong via the Shenzhen Reservoir. Other measures to protect the quality of Dongjiang water have included:

• Constructing sewage treatment plants along Dongjiang to reduce pollution.
• Removing factories from the vicinity of Dongjiang.
• Moving the water intake upstream, where the water quality is better.
• Commissioning the Bio-nitrification Plant at the Shenzhen Reservoir in early 1999.
• Intercepting waste water flowing into the Shenzhen Reservoir.
• Diverting the discharge of polluted water from the Shima River away from Dongjiang.
• Designating Dongjiang into water resources protection area of Guangdong.
• Setting up video surveillance stations in the periphery of Shenzhen Reservoir to strengthen the control of sudden water quality incidents.

The pollution prevention and control measures undertaken by the Guangdong authorities have significantly improved the quality of the Dongjiang water that is supplied to Hong Kong. The situation is continually monitored to ensure the ongoing effectiveness of these measures.

• More on how aqueduct protects the quality of Dongjiang water
  http://www3.news.gov.hk/ISD/ebulletin/en/category/infrastructureandlogistics/030627/features/html/030627en06001.htm

There are 21 water treatment works in Hong Kong. During the treatment process, raw water is dosed with chemicals such as alum and hydrated lime for coagulation and flocculation to remove impurities. Clarified water then flows into rapid gravity filters of sand and anthracite to remove fine particles, after which chlorine and hydrated lime are added for disinfection and pH adjustment. Fluoride is also added to minimise the risk of dental decay. A small amount of residual chlorine is maintained in the treated water to prevent contamination in its journey to your tap.

• More on the treatment process
  http://www.wsd.gov.hk/en/html/water/treatment.htm
• More on the distribution process and water pressure
  http://www.wsd.gov.hk/en/html/water/hkwstc.htm

Hong Kong enjoys one of the safest water supplies in the world. The Water Supplies Department has a comprehensive programme to monitor water quality from collection, to water treatment processes and on to distribution to consumers. Water samples are taken regularly throughout the entire supply and distribution system. The sampling points include water treatment works, service reservoirs, trunk mains, connection points and domestic taps. The data from these samples are checked against the World Health Organization's Guidelines for Drinking-water Quality, which were developed by experts from around the world. With this international standard of reference, you can rest assured that the water in your home is safe for consumption.

• More on drinking-water quality control and the World Health Organization guidelines
  http://www.wsd.gov.hk/en/html/water/control.htm
• Drinking water quality data
  http://www.wsd.gov.hk/en/html/water/qualitydata.htm

The water that comes out of your taps is amongst the safest in the world, as long as the plumbing in your property is properly maintained. Unlined galvanised steel pipes are prone to rusting and have been banned in new buildings since 1995. If you still have unlined galvanised pipes in your building you should replace them with lined galvanised pipes, copper pipes, stainless steel pipes or polyethylene pipes. You should also watch out for discoloured water emerging from your taps, which is a visible indicator of stagnant water. Running the tap for a few seconds should usually fix this problem, but if it persists you should again consider replacing your pipes.

• Frequently asked questions about domestic water quality
  http://www.wsd.gov.hk/en/html/others/faq_wq.htm