The Ministry of Health established the National Drinking Water Quality Standards (NDWQS) in 1983, with the most recent revision in 2000 due for circulation for use in 2002. The standards stipulate limits for physical, chemical, microbiological and radiological parameters and compliance with these standards is mandatory for all private water suppliers. Supporting documentation is available to ensure effective implementation of the standards and include information on the National Programmed for Drinking Water Quality Surveillance, and the Manual of Drinking Water Quality Surveillance. In addition to the NDWQS the DOE has developed Interim National Water Quality Standards (INWQS) that classifies inland water quality into 5 classes: domestic water supply, fisheries and aquaculture, irrigation, livestock, and recreation, each with its own set of biological, chemical and physical parameters.
INTERIM NATIONAL WATER QUALITY STANDARDS FOR MALAYSIA (INWQS) Parameters | (Units) | Classes | | | l | llA | llB | lll | lV | V | Ammonical Nitrogen | mg/l | 0.1 | 0.3 | 0.3 | 0.9 | 2.7 | > 2 | BOD | mg/l | 1 | 3 | 3 | 6 | 12 | > 12 | COD | mg/l | 10 | 25 | 25 | 50 | 100 | > 100 | DO | mg/l | 7 | 5 - 7 | 5 - 7 | 3 - 5 | < 3 | < 1 | pH | - | 6.5-8.5 | 6.5 - 9.5 | 6 - 9 | 5 - 9 | 5 - 9 | | Colour | TCU | 15 | 150 | 150 | | | | Electrical Conductivity | mmhos/cm | 1000 | 1000 | | - | 6000 | - | Floatables | - | N | N | N | - | - | - | Odour | - | N | N | N | - | - | - | Salinity | o/oo | 0.5 | 1 | - | - | - | - | Taste | - | N | N | N | - | - | - | Total Dissolved Solids | mg/l | 500 | 1000 | - | - | - | - | Total Suspended Solids | mg/l | 25 | 50 | 50 | 150 | 300 | > 300 | Temperature | oC | - | Normal +2 | - | Normal+2 | - | - | Turbidity | NTU | 5 | 50 | 50 | - | - | - | Faecal Caliform* | counts/100ml | 10 | 100 | 400 | 5000(2000)@ |