Drinking water 3 Bhim Datta municipality 1 Biofilm 1 Case study 1 Disinfectants - Toxicity 1 Distribution system 1 Drinking Water 1 Drinking water of Pokhara 1 Epidemiologic Studies 1 Kanchanpur district 1 Manuals 1 Pathogen 1 Riask Assessment 1 Series 1 The main objectives of this study were the assessment of the quality of Kathmandu drinking water and the identification of the weak points the city water supply, through a seven months monitoring. The most alarming discovery was that in almost all the places of the city the bacteriological quality of the water is far away from the safety value. The old part of the city shows the highest degree of contamination and this is due to the extremely poor condition of the distribution system in that area. Drinking water gets bacteriologically polluted mostly in the pipelines for the infiltration of sewage and polluted water through leakages back siphonage, and the degree of contamination increases dramatically during monsoon. During the study samples of stored water from seven hospitals were also collected and analyzed. They were found being more contaminated than those collected from public taps, thus pointing out that the degree of bacteriological pollution increases during the storage. However, it has been noted that sometimes the disinfection practices at the treatment plants are not so effective for the high variability of the chemical composition of the water and the presence of high amounts of some chemical components. Especially iron, ammonia and organic matter affect directly the quality of water and more over, decrease the effectiveness of the treatment processes. In such a situation the risk of an outbreak of water borne epidemics is serious and real at any time, and the danger increases during the rainy season. Actions are needed in order to improve the situation and to safeguard public health 1 Water pollution 1 Water quality 1 Water supply standards 1 World Health Organization 1 disinfectants - Chemistry 1