In Malaysia extensive use has been made of primary treatment systems such as communal septic tanks and imhoff tanks and unreliable low cost secondary systems such as oxidation ponds. In addition, large urban areas utilize Individual Septic Tanks (IST). It is estimated that there are over one million individual septic tanks in Malaysia.

These tanks only partially treat sewage, discharging an effluent still rich in organic material. This has the potential to create public health and environmental problems, particularly in urban areas.

IWK is responsible for planning and rationalizing the public sewerage facilities to reduce the number of treatment plants using the "multipoint concept" or regionalization. Finally, sewerage pipeline networks will be layed in urban areas currently serviced by IST to convey the domestic sewage to modern secondary treatment facilities.

In Malaysia, 38% of public sewage treatment plants in the country are mechanical plants. These plants operate using mechanical equipment that accelerates sewage break down.

It is hoped that in the long-term, Malaysia's sewerage system will be made more efficient through the standardization of the types of plants used.

These extensive programs are nothing short of a revolution in the management of domestic sewage in Malaysia. The entire sewerage infrastructure can expect to undergo changes. Estimates have been made of the number and type of public treatment plants currently in Malaysia.