A probability based end-use model was constructed as part of this study to derive diurnal residential indoor water demand patterns on a temporal scale of 10 seconds. The end-use model derived the water demand patterns by aggregating the synthesised end-use events of six residential indoor end-uses of water in terms of the water volume required, duration and the time of occurrence of each event. The probability distributions describing the end-use model parameters were derived from actual end-use measurements that had previously been collected by others in a noteworthy North-American end-use project. The original comprehensive database, which included water measurements from both indoor and outdoor end-uses, was purchased for use in this project. A single execution of the end-use model resulted in the synthesised diurnal water demand pattern for a single household. A Monte Carlo method was applied to obtain 99,500 water demand patterns. The end-use model presented in this study yielded realistic indoor water demand estimations when compared to publications from literature, and the work could be extended in future to include outdoor water demand and sensitivity to water distribution system pressure.