In April 2016, residents of the housing area in Balok Baru were awakened by water discolouration as the Nyior River’s water turned black and released an unpleasant odour. According to the investigation report issued by the Department of Environment, it was found that the Nyior River was contaminated with E coli bacteria. The high content of E coli in the Nyior River proves that the water was contaminated with untreated sewage water and chemicals.

This case of river pollution due to untreated sewage was not the first time it had happened in Malaysia. In fact, such cases have occurred in Sungai Batu Ferringhi, George Town.

The discharge of untreated waste water into the river is caused by an improper sewerage system and the irresponsibility of residents to empty their septic tanks. According to a study carried out on residents at Balok Baru, most of them have not desludged their septic tanks for almost three years.

Actually, the Individual Septic Tank (IST) should be desludged regularly, ie every two years. Individual septic tanks have two main chambers. The first chamber is where solids from sewage will be forming ‘sludge’, while grease and oil will form a layer of scum on the surface. Effluent between the layers of scum and sludge will flow to the second chamber and subsequently be discharged into drains or be absorbed into the soil.

The room provided in individual septic tanks can only accommodate sludge and scum up to two years. Hence, if an individual septic tank has not been emptied in the last two years, it might cause the overflowing of sludge. The overflowing sludge will be flowing together with effluent into drains and eventually pollute a nearby river.

Regular desludging is important for preserving the environment, protecting water resources and maintaining good health. This is because untreated sewage contains pathogens such as viruses, bacteria and parasites at very high content. It is said that one gram of faeces contains 10 million viruses, 1 million bacteria, 1000 parasite and 100 worm eggs. Sewage water also contains chemicals such as detergents.

The pollutants contained in the waste water caused the unpleasant odours and turned the colour of the river to black. Long-term exposure to untreated sewage water can cause a person to suffer from health problems, such as diarrhea, cholera, typhoid and Hepatitis A. It is said that 50 percent of 9,000,000 child deaths are caused by unmanageable sewage.

Besides, the discharge of untreated sewage water may affect aquatic life in the river. Indirectly, such contamination can also affect the socio-economic activities of the surrounding area due to the unbearable stench. Overflowed effluent from the inefficient septic tank is not only affecting the river, but it also impacts on groundwater.

The flowing of sludge along the effluent will seep into the ground and the situation worsens during rainfall. The rain will drain the overflowing sludge into the river.

Therefore, it is very important for every individual septic tank to be emptied regularly to ensure the well-being of the surrounding communities, and thus preserve the environment. As responsible consumers, we need to take our responsibility to desludge our septic tanks.

NUR IMANI ABDULLAH is research and policy executive - water and energy, Federation of Malaysian Consumers Associations (Fomca), Petaling Jaya.