In the previous report, we investigated water supply characteristics such as flow rate and water supply time of a water-saving toilet and urinal, which are currently adopted mainstream, and attempted to apply a water fixture unit to them based on the fundamental principle proposed by Hunter. The results, revealed that the newly suggested water supply fixture unit is smaller than the original unit proposed by Hunter. In this report, we performed load calculations for real buildings with these proposed water supply fixture units and original water supply fixture units and exmamined the reduction rate of the total number of fixture units and amount of water supply load. Furthermore, we investigated the improvement in prediction accuracy of water supply load by comparing the calculated values with the measured values. The results, we revealed that it is possible to reduce the total number of water supply fixture units by a maximum of approximately 58%, and the calculated water supply load value by approximately 30%. Thus, ratio of the calculated to the measured value of water supply load can be smaller.