Since the independence resumption of Latvia in 1990, water consumption in the country has decreased considerably. Accordingly, domestic hot water consumption in the household sector reduced. The main reasons for the decrease of domestic hot water consumption are installation of consumption meters in apartments resulting in payment for the real consumption, increase of prices of hot water and heat. The paper provides the results of hot water consumption measurements in a dwelling house in Riga. The results were obtained using the prescribed formulas of building normative LBN 221-98. The fluctuations of irregularity coefficient depending on hot water consumption changes were analyzed in this research; as well as hot water consumption fluctuations during the day, and the maximum consumption value. The results of measurements show that the actual domestic hot water consumption data differs noticeably from the normative values.