Purpose – The thesis is intended to provide a comprehensive overview of the contamination events in the aircraft drinking water systems as well as to uncover their possible causes. --- Methodology – The different types of contamination in aircraft drinking water is investigated and their presence verified by reliable studies and laboratory results. Furthermore, the effec tiveness of the disinfection processes used will be investigated. --- Findings – Many commercial aircraft carry unclean drinking water that deviates significantly from the specified limits. It is not uncommon for airlines not to initiate the necessary disinfec tion measures in cases of concrete suspicion. Even the prescribed follow-up tests are often not carried out. In addition, the disinfection of the aircraft drinking water system often requires several passes, which results in higher maintenance costs. --- Practical implications – Drinking water systems need to be inspected at shorter maintenance intervals to resolve advancing contamination. Better monitoring programs must also be put in place to protect passengers from contaminated drinking water on aircraft. --- Social implications – Passengers and crew members should limit their use of drinking water as much as possible based on current data. --- Originality – The work provides for the first time a comprehensive overview of the potential contamination of aircraft drinking water systems.