Water is one of the most precious resources on this planet and is becoming increasingly scarce in the semi-arid state of California. But much of the water we use ends up as wastewater. Wastewater is produced when we use sinks, showers, toilets, appliances, and machinery in our homes, shops, offices and factories.
What is recycled water? Recycled water is wastewater that has been purified through a high level of treatment. This processed water is treated to strict standards set by the California Department of Health Services and is constantly monitored by local, state, and federal regulatory agencies to ensure it continuously meets those standards.
Recycled water has been found safe for irrigation, industrial and agricultural uses. In fact, all water on Earth is in some way recycled. Mother Nature has been recycling water and wastewater for millions of years through a natural cleansing process of sedimentation, organic consumption, natural filtration and disinfection. Modern wastewater treatment technology essentially speeds up this natural process.
How is recycled water treated? Wastewater from homes and business in East Palo Alto, Los Altos, Los Altos Hills, Mountain View and Palo Alto is piped through sanitary sewers to the Regional Water Quality Control Plant where it undergoes primary, secondary, advanced stages of treatment. The water that is used for reclaimed water undergoes additional treatment.
Primary treatment (screening and sedimentation) is a gravity process that allows solid matter to either float to the top or settle to the bottom and is then removed.
Secondary treatment (biological treatment) uses bacteria to digest dissolved organic matter and small waste particles that are too light to settle out. As these bacteria eat and grow, they fall to the bottom, leaving water that is at least 95 percent pure.
Advanced treatment uses multi-layered filter bed (sand and coal) to remove any remaining suspended particles. Chlorine is a disinfectant used to destroy bacteria, viruses, and other pathogens. The water is 99 percent pure at this state and meets or exceeds many drinking water standards.
Reclaimed water treatment uses a polymer to decrease the amount of total dissolved solids. The water is then filtered for a second time through a multi-layered filter bed.
Recycled Water helps Preserve Saltwater and Tidal Marshland Habitats
Reducing the amount of treated wastewater discharged into the South Bay decreases the impacts on saltwater marshes. When treated wastewater is discharged into South Bay marshes, it can decrease the salinity and alter the plant communities that grow there. Using treated water for irrigation helps preserve Palo Alto's saltwater marshlands, the sensitive habitat of two endangered species, the California clapper rail and the salt marsh harvest mouse.
Recycled Water decreases diversion of water from our environmentally-sensitive ecosystems
Palo Alto residents' water supply originates from the Hetch Hetchy within the Eastern Sierras near Yosemite. The use of recycled water may alleviate the pressure on environmentally sensitive ecosystems in the future.
Microcontaminants in the Environment There are microcontaminants found in reclaimed water, including persistent organic compounds. Due to concerns about the existence of such compounds in reclaimed water, Program staff monitor research regarding treatment technologies, mechanisms of human exposure, and health risk assessments to ensure that reuse practices protect human health and the environment. The use of recycled water for landscape purposes is not a direct exposure route for these compounds to the aquatic environment; the soil provides one more step in the treatment process.
Rules And Regulations The Recycled Water Program meets and exceeds standards set by the California Department of Health Services.
The California Department of Health Services (DHS) has a strict water quality criteria for recycled water. DHS has concluded that water meeting those criteria is safe for a variety of uses, including landscape irrigation. The reclaimed water meets or exceeds all the criteria, and employs additional precautions to minimize human contact with the water.
Precautions include:
Nighttime irrigation.
Advisory signs prominantly posted at each facility entrance. Irrigation systems designed to minimize overspray, runoff, and ponding.
No cross-connections allowed between the recycled water pipes and any other water system.
Recycled water pipes installed after 1993 are colored purple and labeled with the words, "RECYCLED WATER - DO NOT DRINK."
No hose connectors are allowed on pipes that are accessible by the public.
Spray, mist, or runoff is not allowed to enter outdoor eating areas, drinking fountains, dwellings, or food handling facilities
For additional information on rules and regulations related to recycled water see California Health Laws Related to Recycled Water.
