Role of operational changes in forming discoloured water in a water distribution system

The majority of customer complaints received by water companies in Australia and in many parts of the world are of discoloured water. South East Water Ltd., in Melbourne Australia, has under-taken a study to understand discoloured water formation with the aim of reducing the incidences of discoloured water and associated customer complaints. The changes that occur to the water as it travels through a water distribution system may lead to the formation of discoloured water. This paper explores the extent to which known operational events such as burst mains, contributed to these water quality changes and thereby cause discoloured water and associated customer complaints. Continuous online monitoring of flow rate and turbidity at six locations in a water quality zone in the South East Water region were compared to recorded operational events and customer complaints over a 16-month period. It was found that operational changes were attributed to causing over a third of discoloured water events and a smaller proportion of customer complaints. Such results indicate the need for a review of the current operational practices, particularly flushing, and show that not all discoloured water is created by the resuspension of sediment by high velocities.