Or sewer to spigot. Take your choice of how critics have labeled plans in the past to turn wastewater into drinking water. The idea is back again as several areas of the country are facing water shortages. Water - the something to be fought over in the future.

But cities considering large-scale systems that recycle wastewater to drinking standards may face an uphill battle. Such initiatives — dubbed “toilet to tap” proposals by critics — have encountered resistance in the past as a result of cost and the overall yuck factor. In 2001, Los Angeles scrapped a $55 million wastewater-recycling project that would have provided the equivalent of the annual water needs of 200,000 city residents. A similar proposal in San Diego was derailed in the late 1990s amid an outcry that poor neighborhoods would be forced to use the wastewater from rich neighborhoods.

The cost of such projects may also be tough for residents to swallow. In Miami-Dade County, the estimated price tag on a new wastewater-recycling system is $350 million. It is unclear how this will affect the water bills of residents, though local officials expect rates to rise.