Solar water disinfection - the SODIS method - is a simple procedure to disinfect drinking water. Contaminated water is filled in a transparent PET-bottle or glass bottle and exposed to the sun for 6 hours. During this time, the UVA radiation of the sun kills enteric bacterial pathogens. The SODIS method helps to prevent diarrhea and thereby is saving lives of people. In this thesis, the disinfection process during SODIS was analyzed with the latest culture-independent methods. Viability indicators suggested that membrane functions play a crucial role during disinfection. The respiratory chain...