Treatment Process & Delivery

How it works

Upon arrival at the treatment plant, the "wastewater" is cleaned through various processes, which mimic how nature repurifies water, before it can be discharged safely into the San Francisco Bay or used for landscape irrigation and industrial applications. There are three treatment steps that wastewater goes through before it is considered recycled -- primary treatment, secondary treatment, and tertiary-treatment. The steps included in primary treatment are prechlorination (for odor control), screening (to remove large objects), grit removal, and primary sedimentation. Secondary treatment uses "good" bacteria to remove approximately 95-98 percent of the remaining solids and organic material. Tertiary treatment at DERWA employs sand filtration to remove particulate matter and ultraviolet disinfection to destroy inactive bacteria, viruses, and other pathogens such as Cryptosporidium.

The Treament Process Fact Sheet provides greater explanation and detail regarding the treatment processes utilized by the SRVRWP.

Purple Pipe System

Guidelines set by the California Department of Health Services mandate that recycled water facilities be clearly distinguishable from drinking water facilities to help prevent the two supplies from being accidentally connected. Pipes, sprinkler heads, pump, valve box covers and other devices used in the recycled water system are purple colored or tagged and labeled with the words "Reclaimed Water - Do Not Drink."

Clear and prominent signage throughout the irrigation areas ensures that the public can easily identify recycled water systems.