Abstract
This paper considers the probability of power supply failures at bulk water distribution pump stations. Electrical power supply is important within the bulk water distribution environment, particularly when pumping is required. Reliability of power supply is commonly expressed by means of indices, such as amongst others, the SAIDI and SAIFI indices as defined by the Institute of Electrical and Electronics Engineering (IEEE). These indices are used to calculate the probability of failure associated with power supply. Data was obtained from a number of sources and used to benchmark the reliability of South African power supply against that of other countries. The reliability of power supply from seven South African Water Board (Rand Water) pump stations is also analysed. Limited data seems to be available that allows one to quantify the reliability of pump systems, taking into account the reliability of the various system components.