The average percentages of non-revenue water (NRW) for Malaysia and for the state of Perak in 2010 were 36.37 and 29.44%, respectively. These average percentages have led to lower income generation. This could create constraints on maintenance and operation of water reticulation systems. In this study, the appropriate time band of minimum night flow (MNF) and the actual water loss or amount of NRW for the district of Kinta in Perak, Malaysia were investigated. Flow and pressure in 361 zones in Perak were monitored for 24 h using PrimeWorks software. From the 361 zones, 30 study zones were randomly selected. The 30 study zones were geographically divided into three groups, with each group having 10 zones. Statistically, one-way analysis of variance (ANOVA) was used to test the variations in MNF among the three groups. The data of the flow for the 30 zones were screened from 1:00 to 5:00 am for the past 4 years. The frequency of MNF occurrences was analyzed every 15 min. The results show that the majority (84.2%) of the frequencies of MNF occurrences in the 30 study areas occurred from 2:15 to 4:15 am, whereas minimum frequencies were observed at 1:00, 1:15, and 5:00 am.