WATER FROM MAHAWELI, BADULU AND KELANI RIVERS UNSUITABLE FOR CONSUMPTION

Sri Lanka's main water sources that supply drinking water have become polluted.

- By Prageeth Sampath Karunathilaka and Sudharika Gurusinghe

Recent findings indicate that consuming water from these sources without proper treatment could lead to serious issues. A study conducted by the University of Peradeniya in 2023 examined the extent of this pollution, focusing on the how the presence of bacteria and other harmful substances in the water affects the water sources.

Water samples from the Kelani, Mahaweli and Badulu rivers were subject to research during the analysis.

One of the objectives of the study was to assess the level of bacterial contamination in the Mahaweli River, the main supplier of drinking water to the hill country.

The researchers tested both surface water and treated water from 14 drinking water treatment plants (DWTPs) located along the river segment of 60 km between the Kotmale and Victoria reservoirs. These tests measured total bacterial count (TBC), total coliform count (TCC), and fecal coliform count (FCC).

Testing of the surface water of the river confirmed significant contamination variations of TBCS, TCCs and FCCs between dry and wet season. This is due to point source discharges and drains that carry septic waste. The spread of bacteria also increased during the wet season due to the diffusion of contaminated bacteria with the runoff. The study was conducted clustering the locations of DWTPs into three (3) categories according to microbial contamination as very low (Kotagala, ThalawakelleGalkanda, Kandy South, Pundaluoya, Ulapane, Greater Kandy), moderate (Nawalapitiya, Paradeka, Elpitiya, Nillambe, Balagolla, Haragama, University Plant, Polgolla) and high (Thalawakelle-Nanuoya).