Modelling the risk of contaminant intrusion in water mains Available to Purchase

The contamination of water distribution systems is widely recognised in the case of intermittent water supplies, where pipes are empty for many hours each day and thus under negligible or zero pressure. This allows contaminants from pollution sources such as sewers, open drains and surface water bodies to enter into the water distribution pipes through leaks and cracks during non-supply hours. In developing countries, where water supply is intermittent, contamination frequently occurs to the distribution network at unacceptably high levels, posing a threat to public health. The urban poor suffer most from contaminated water supplies and also suffer a far greater health burden, related in part to the consumption of poor quality water. There are no tools currently available to assist engineers in identifying the risks associated with contaminant intrusion into intermittent water distribution systems. This paper introduces a new tool called integrated risk assessment of water distribution systems (IRA-WDS). It is anticipated that the application of such tools will enable engineers to manage water quality more effectively by developing appropriate control measures to minimise the risks of contaminant intrusion. This paper summarises details of the mathematical models that form the basis of IRA-WDS and also describes the application of the tool to a real case study in India. The outputs from IRA-WDS are risk maps showing the risk of contaminant intrusion into the various parts of the water distribution system and an understanding of the main factors that contribute to risk. These risk maps will be invaluable to decision makers in that they can provide a guide to prioritise the operation and maintenance strategy in order to improve water quality.