Ukraine traditionally suffers from acute shortage of quality drinking water, and this problem has intensified recently due to military operations on its territory. The lack of water laboratories in the combat area made it impossible to monitor the quality of drinking water. Due to the pollution of water resources and the destruction of water supply systems, the population is forced to use water unsuitable for drinking. One of the important indicators of pollution is the high iron content in drinking water, which exceeds the maximum permissible standards in many regions of Ukraine. To analyze the iron content in water, the spectrophotometric method with 1,10-phenanthroline was chosen, which is simplest, less labor-intensive and energy-consuming. If it is impossible to carry out the analysis at the point of water sampling, the result obtained has a high error due to a decrease in the concentration of iron in the water over time. The reason for this effect is the rapid transition of iron from soluble to insoluble form. The aim of the research is to study the influence of temperature and acidity on the dynamics of iron concentration in drinking water and to develop recommendations for analyzing water for iron content in laboratory conditions. It has been proven that drinking water must be acidified to a level of pH =1 immediately after water sampling. In the case of analyzing previously unacidified water, it should be heated to a temperature of 40°C or higher in the presence of hydrochloric acid. It was established that the amount of total iron in the analyzed water exceeds the amount of dissolved iron by 6.4 times. The correspondence of drinking water with the requirements of the standard for iron content can only be established by determining the content of total iron in all its species.