It is well known that polluted water is dangerous to health. Pollution of fresh water ecosystems is often the cause of diseases, and therefore a multidisciplinary approach involving hydrology, engineering, urban planning and public health is necessary for a good public health outcome. It has been recognized that a water supply system is connected with the improvement of public health of the population. Can diseases such as diarrhea in isolated rural areas or malaria in Africa be prevented through good water supply management? There is an opinion that water supply management is also public health management and that it is a very good tool in reducing and controlling diseases and will definitely play a big role in the future. Protected drinking water is essential for public health. The most common microorganisms associated with waterborne diseases are: Campylobacter, Legionella, Cryptosporidium, Norovirus, E. coli and Giardia. Legionella has been proven to be one of the most important causes of diseases associated with the water supply systems. Investing in water infrastructure is therefore investing in the safety of drinking water, which is the basis of public health, and its pollution can even lead to a potential epidemic caused by various microorganisms. The paper will present the most common diseases that can potentially be transmitted through the public water supply system, as well as the differences in the infrastructure in different parts of the world, which play a major role in public health of the population. The importance of a good water supply system and the environment in preventing diseases that are potentially spread by contaminated drinking water will be shown. Also, possible dangers of contamination of drinking water that the population uses on a daily basis will be pointed out.