This graduate thesis investigates the complex topic of corrosion of water supply systems, which are a key part of urban infrastructure responsible for ensuring a safe supply of drinking water. Preserving the structural integrity of water pipes, especially those with uninsulated inner walls, is a key concern in order to maintain a reliable water supply and prevent the harmful effects of internal corrosion. It is important to emphasize that each water supply system represents a unique environment that shapes the nuances of the corrosion process. In this case, the focus is on a steel water pipe from the coastal area of northern Croatia. The appearance of the pipe reveals noticeable signs of deterioration, including visible changes in the thickness profile in certain places, changes in color and the presence of various deposits. Furthermore, the peeling of a heterogeneous layer of pipe corrosion products is observed, adding to the complexity of the studied phenomenon. The multi-layered investigation of the observed corrosion damage included a number of analytical techniques, from Fourier-transform-infrared spectroscopy (FTIR), digital microscopy, and scanning electron microscopy (SEM), to energy-dispersive X-ray spectroscopy (EDS). In addition, a test for the presence of sulphides/carbonates was carried out with lead acetate indicator paper and the determination of the water quality index using the Langelier saturation index (LSI). With its results, the research contributes to the understanding of the specifics of corrosion damages in water pipes and the parameters of the environment in which these damages occur. Understanding the causes of internal corrosion mechanisms is vital to properly manage and extend the life of water-transporting pipeline systems.