Prior to the passage of the U.S. Safe Drinking Water Act of 1974, the focus of most of the water utilities was on treating water, even though it has long been recognized that water quality can deteriorate in the distribution system. However, after the SDWA was amended in 1986, a number of rules and regulations were promulgated which had direct impact on water quality in distribution systems. To decrease what was considered an unreasonably high risk of waterborne illness, the U.S. EPA promulgated the Total Coliform Rule (TCR), and Surface Water Treatment Rule (SWTR) in 1989 (U.S. EPA, 1989a & b). More recently there has been an increased focus on distribution systems and their importance in maintaining water quality in drinking water distribution systems. There has also been general agreement that the most vulnerable part of a water supply system is the distribution network.
This chapter discusses the general features associated with water supply distribution systems, including design considerations, points of vulnerability to accidental or deliberate contamination, and the potential for using network modeling to assess system vulnerability. The role of tanks and storage reservoirs in operating and managing water systems is discussed, including their effect on water quality. Water quality models and their potential for use in tracking and predicting water quality movement and changes in water quality are examined. Because a key aspect of assessing the performance of drinking water systems is the response of the network and the resulting network model to the pattern of...
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