Dual Water Distribution Systems

In addition to handling current domestic and irrigation demands, water distribution systems must also accommodate future needs as well as provide reserves for firefighting and other emergencies. However, the delivery of these increased quantities of safe drinking water is becoming increasingly more challenging and burdensome for the water utilities. The combination of increasingly stringent Maximum Contaminant Levels (MCL) requirements, system-induced quality deterioration, and reductions in high quality water sources has severely complicated the utility's task of delivering drinking water that meets Safe Drinking Water Act (SWDA) water quality standards. As utilities expand their existing plants and/or invest in new technologies to meet these water quality challenges, these additional costs must be passed on to the users as rate hikes.

Most water distribution systems employ a traditional approach in which all water is treated at a centralized location and then distributed through a series of pipelines. Under this approach, all of the water leaving the plant must be treated at a level that meets the current drinking water standards specified under the SDWA. Economically, the centralized approach is very expensive in that, even the water used in non-human contact applications such as irrigation and toilet flushing, must also be treated to meet drinking water standards. One proposed solution to these problems involves the selective introduction of dual distribution systems in which a single pipe is used exclusively for potable drinking water applications with a larger pipe transporting bulk water for applications such as fire-fighting, toilet flushing, and irrigation.