The Guidelines cover a broad range of chemicals that can affect drinking water quality but not all chemicals will be relevant within a country. To learn more about the list of chemicals, their guideline values and its hazards in drinking water, please click here.
The Government currently adopts the corresponding guideline values / provisional guidline values in the 4th edition of the WHO”s Guidelines published in 2011 as the Hong Kong Drinking Water Standards. Details can be found here.
pH is a measure of how acidic/basic water. pH ranges from 0 to 14, with 7 being neural. pH of less than 7 indicates acidity, whereas a pH greater than 7 indicates a base solution. Pure water is neutral, with a pH close to 7.0 at 25°C. Normal rainfall has a pH of approximately 5.6 (slightly acidic) owing to atmospheric carbon dioxide gas. Safe ranges of pH for drinking water are from 6.5 to 8.5 for domestic use.
A high pH makes the taste bitter and decreases the effectiveness of the chlorine disinfection. Low-pH water will corrode or dissolve metals and other substances.
Turbidity is a measure of the ability of light to pass through water. The particulates can provide hiding places for harmful microorganisms and thereby shield them from the disinfection process. Suspended particles provide adsorption media for heavy metals such as mercury, chromium, lead, cadmium, and many hazardous organic pollutants.
Turbidity more than 5 NTU can be visible to the average person while turbidity in muddy water, it exceeds 100 NTU.