As seen in ESRI Map Book Volume 33: 
This map is an "E-size" print of the Temecula Valley Regional Water Reclamation Facility, showing GIS features for all structures, roads, land use areas, and flow directions. The purpose of this map is to quickly summarize the journey that our sewer system goes through, on its way to becoming recycled, or reclaimed, water. This process is very important to our infrastructure in Southern California, because it is used to save our precious potable water supply.