Since the independence resumption of Latvia in 1990, water consumption in the country has decreased in many times. Accordingly, domestic hot water consumption in the household sector reduced. In this paper there are presented the results of domestic hot water consumption measurements (6 days), which were done in a multi-compartment dwelling house in Riga. The results were worked up using the prescribed formulas of building normative LBN 221-98. The fluctuations of irregularity coefficient depending on domestic hot water consumption decrease was analysed in this research; as well as domestic hot water consumption fluctuations in the day time and the maximal consumption value. Using the received results, domestic hot water consumption diagrams for daily conditions were prepared.