The quality of drinking water has always been an extremely topical problem for the eastern regions of Ukraine. In the region of hostilities, the population receives drinking water of unsatisfactory quality. The evacuation of environmental and water laboratories from the region of hostilities made it impossible to monitor the quality of drinking water. The influence of temperature and acidity on the dynamics of iron concentration in drinking water as well as the process of transition of iron into an insoluble form were studied by spectrophotometric method with 1,10-phenanthroline. It is recommended to preserve drinking water with acid to the level of pH = 1 under the impossibility to carry out analysis immediately after collecting water samples. It has been established that for an unacidified water sample, it should be heated immediately before analysis in the presence of hydrochloric acid. Correspondence of drinking water with quality requirements for iron content can only be established by determining the content of total iron in all its species.