Malaysian Water Quality Standard
Updated: Mar 30, 2022
Water Quality
Water quality refers to the chemical, physical, biological, and radiological characteristics of water.
It is a measure of the condition of water relative to the requirements of one or more biotic species or to any human need or purpose.
It is most frequently used by reference to a set of standards against which compliance, generally achieved through treatment of the water, can be assessed.
The most common standards used to assess water quality relate to the health of ecosystems, safety of human contact, and drinking water.
Department of Environment (DOE) Malaysia
The Department of Environmet (DOE) (https://www.doe.gov.my/portalv1/) is an agency responsible for promoting, conservation and sustaining sound environmental management in the process of nation bulding and ensuring the environment is always clean, healthy and safe for the well-being of the people.
National Water Quality Standards For Malaysia
The national water quality standard for Malaysia is set by the DOE. The DOE set limits on parameters according to water classes.
The DOE divides water into 5 classes according to use:
Class | Uses |
|---|---|
Class I | Conservation of natural environment. Water Supply I - Practically no treatment necessary Fishery I - Very sensitive aquatic species |
Class IIA | Water Supply II - Conventional treatment required. Fishery II - Sensitive aquatic species |
Class IIB | Recreational use with body contact |
Class III | Water Supply III - Extensive treatment required. Fishery III - Common, of economic vaue and tolerant species; livestock drinking |
Class IV | Irrigation |
Class V | None of the above |
The limits are as below:
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Water Quality Index
Water quality index (WQI) provides a single number that expresses the overall water quality, at a certain location and time, based on several water quality parameters. The objective of WQI is to turn complex water quality data into information that is understandable and usable by the public.
The DOE sets the water quality index based on water class:
Parameter | Class I | Class II | Class III | Class IV | Class IV |
Ammoniacal Nitrogen | <o.1 mg/L | 0.1 mg/L to 0.3 mg/L | 0.3 mg/L to 0.9 mg/L | 0.9 mg/L to 2.7 mg/L | >2.7 mg/L |
BOD | <1 mg/L | 1 mg/L to 3 mg/L | 3 mg/L to 6 mg/L | 6 mg/L to 12 mg/L | >12 mg/L |
COD | <10 mg/L | 10 mg/L to 25 mg/L | 25 mg/L to 50 mg/L | 50 mg/L to 100 mg/L | >100 mg/L |
pH | <7 | 6-7 | 5-6 | <5 | >5 |
Dissolved Oxygen | >7 mg/L | 5 mg/L to 7 mg/L | 3 mg/L to 5 mg/L | 1 mg/L to 3 mg/L | <1 mg/L |
Total Suspended Solids | <25 mg/L | 25 mg/L to 50 mg/L | 50 mg/L to 150 mg/L | 150 mg/L to 300 mg/L | >300 mg/L |
Water Quality Index | <92.7 | 76.5 to 92.7 | 51.9 to 76.5 | 31.0 to 51.9 | >31.0 |
Drinking Water Quality Standard
The Department Of Environment (DOE) Malaysia is responsible for making sure that public water supplies within Malaysia are safe. In 1983, in response to the need for a realistic and appropriate set of guidelines regarding safe and potable water supply throughout Malaysia, the Drinking Water Quality Surveillance Unit, Engineering Services Division, Ministry of Health Malaysia prepared a set of guidelines.
Water for drinking, culinary and other domestic use should be safe, palatable and aesthetically appealing. The aim of this document is thus, to set limits to the constituents that may be present in water, which may be hazardous to health or objectionable to the physical senses of the consumer.
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