Hong Kong's raw water (including Dongjiang (“DJ”) water and rainfall collected from local gathering grounds) undergoes rigorous treatment processes including coagulation / sedimentation, filtration and disinfection to ensure that the quality of drinking water provided to customers complies fully with the Hong Kong Drinking Water Standards.
Drinking water quality, however, can be affected by the condition of a building’s inside service. To safeguard tap water quality, property owners and building managers are advised to carry out proper maintenance of inside service and regular cleaning of water storage tanks.
Over the years, the WSD has been supplying drinking water in full compliance with the World Health Organization’s Guidelines for Drinking-water Quality (“WHO Guidelines”).
In September 2017, the Government adopted the guideline values / provisional guideline values of the 92 parameters in the WHO Guidelines as the Hong Kong Drinking Water Standards (“HKDWS”).
With reference to the WHO’s advocacy, the Government commissioned an expert consultant earlier on to conduct a review, including making reference to international practices, to establish a set of drinking water standards suitable for adoption in the local context. Based on the expert consultant’s findings and recommendations, the Government has announced the latest HKDWS on 22 April 2021. Please visit the HKDWS webpage for details.
The WSD has developed a comprehensive and extensive water quality monitoring regime through a series of physical, chemical, bacteriological, biological and radiological examinations covering the HKDWS and the additional parameters for water quality surveillance and operational monitoring.
Water quality throughout the entire water treatment, supply and distribution system is systematically monitored by above series of examinations of water samples taken at catchment, intakes, receiving point of DJ water at Muk Wu Pumping Station, impounding reservoirs, water treatment works, service reservoirs, water distribution systems and consumers’ taps. Please refer to the Key Facts webpage for details on the number of samples taken and tested.
The WSD laboratories have been equipped with advanced analytical instruments for trace analysis of various contaminants.
In addition, the WSD has developed innovative and efficient water quality monitoring technologies, which have enhanced the department's efficiency in water safety monitoring.
The WSD publishes drinking water quality data according to its monitoring results on its website. Drinking water quality data in the preceding 12-month period are published half-yearly. The drinking water quality data for the period of April 2023 to March 2024 are as follows:
For the water quality data of DJ water, please refer to the Dongjiang Water webpage.
