In September 2017, the Government adopted the respective guideline values/provisional guideline values in the World Health Organization (“WHO”)'s Guidelines for Drinking-water Quality (“Guidelines”) as the first Hong Kong Drinking Water Standards (“HKDWS”) and established a systemic revision framework for the review of HKDWS (see Figure 1 below).

Figure 1: Revision Framework of HKDWS

According to the revision framework, the Drinking Water Safety Advisory Committee ("DWSAC") will also advise the Development Bureau on the review of HKDWS.

Upon the recommendation of the expert consultant and affirmation of DWSAC, the Government subsequently updated HKDWS in 2021 with the number of water quality parameters revised from 92 to 60, which includes the addition of two new parameters, namely perchlorate and total trihalomethanes, and exclusion of 34 parameters irrelevant to Hong Kong.

Latest Update

In response to the revision of the Mainland’s drinking water standard and WHO's Guidelines in 2022, the Government again commissioned an expert consultant to conduct a review of HKDWS. In the process, the updates on drinking water standards/guidelines made by various jurisdictions¹ were also examined. Based on the expert consultant's review findings and recommendations, the Government has formulated the latest HKDWS with the number of water quality parameters revised from 60 to 61, including the addition of three new parameters (namely manganese, cylindrospermopsins and saxitoxins), extension of the coverage of an existing parameter, microcystin-LR, and exclusion of two existing parameters (namely tetrachloroethene and uranium).

¹ These jurisdictions include Australia, Canada, United Kingdom, the European Union, Japan, New Zealand, Singapore and the United States of America.

With the affirmation from DWSAC, the Government announced the above update on 23 April 2025.

For the latest HKDWS, please see Table 1.

Surveillance List, Watch List and Aesthetics Guidelines

In addition to HKDWS, the Government has established the following two other lists and a set of aesthetic guidelines: -

1. Surveillance List (see Table 2) – used for surveillance monitoring and includes parameters with low or even undetectable levels in the drinking water of Hong Kong, which are far below a level that would cause adverse health risk, and microbial parameters which serve to indicate the sanitary of drinking water supply systems; and
2. Watch List (see Table 3) – used for keeping in view of the international development and includes parameters with their potential health risk not yet fully established scientifically.
3. Aesthetic Guidelines (see Table 4) – used for ensuring the aesthetic quality of the drinking water in Hong Kong such as appearance, taste and odour.

The Government will make reference to the local monitoring results and latest worldwide scientific development and review the above-mentioned lists and guidelines from time to time.

Flowchart for Review of Parameters

The flowchart for the review of parameters in HKDWS, the Surveillance List and the Watch List is shown in Figure 2.

Figure 2: Flowchart for review of parameters in HKDWS, the Surveillance List and the Watch List