Assessing the Condition of Water Distribution Mains.

Water is supplied to customers via a distribution network of aging, mainly ferrous water mains. The deterioration in condition of these mains is affected by the internal and external environment to which the mains are exposed. Water utilities are required to report on the condition of these mains to the economic regulator OFWAT on an annual basis. The purpose of this is to determine investment strategy and set customer price limits. Condition assessment is also used within maintenance planning, particularly pipeline rehabilitation. Traditional methods of condition assessment for small diameter ferrous mains are destructive techniques which involve excavation of sections of main, measurement of corrosion damage, and prediction of remaining life.A critical evaluation of the traditional methods of condition assessment has been carried out to identify the problems associated with the techniques, and quantify the sensitivity of the equations used to data accuracy. The data that is collected by Thames Water throughout the routine operation and maintenance of the distribution network has been identified, reviewed, and compared to the parameters identified within the literature as being either a cause or a result of water main corrosion. These data sets were related to either the performance of the system or the environment to which the mains are exposed. The data available within Thames Water were investigated using multiple regression analysis to determine the relationship between pipeline condition, performance and environment. The factors that are related to the deterioration of ferrous water distribution mains, on which data is available within a typical water utility, have been identified. Three equations are proposed for the prediction of the degree of tuberculation within the distribution system and the depth of internal and external from these data sets. Recommendations have been made regarding the potential uses and applications of this technique in the management of water distribution networks and regulatory reporting in England and Wales