Assessment of Coliform, Escherichia coli, and Enterococci in Raw and Treated Water in Negeri Sembilan, and Factors Associated with the Decontamination Procedure

Abstract

World Health Organization estimated that half of the world’s population will encounter water-stressed living areas by the year 2025 due to climate change, population growth, and urbanization which already pose challenges for water supply systems. In Malaysia, water operators for each state are responsible to treat water and supplying it all over the state. This study focused on Negeri Sembilan state which has 21 water treatment plants that are responsible for supplying treated water to consumers. The objectives of this study were to assess microbial contaminants in raw and treated water using a rapid detection method (IDEXX Colilert method for coliform and E. coli detection, and IDEXX Enterolert-DW for enterococci detection in drinking water) and to quantify the number of microorganism with most probable number (MPN) method. A total of 96 samples were collected from both raw (n=17) and treated water (n=79) in Negeri Sembilan. Results have shown that the raw water sample in Seremban recorded the highest number of coliform (7258.8 MPN/100 ml), E. coli (5198.7 MPN/100 ml), and enterococci (997.5 MPN/100 ml). For treated water, all samples were recorded at <1 MPN/100 ml. This showed that the decontamination procedure especially chlorination done by the water treatment plant did reduce the number of microbes in drinking water. Further analysis showed that the level of ammonia did not influence the number of microorganisms. However, the presence of chlorine did reduce the number of microbes, whereas and high level of turbidity showed a high number of microbes. In conclusion, despite the high number of microbes in raw water samples, treatment using chlorine (0.2mg/L to 5.0mg/L) was effective in reducing their numbers (<1 MPN/100 ml) to provide clean water to the consumers.