What is recycled water?
Recycled water is wastewater that is purified through multiple levels of treatment. Recycled water is clean, clear, and safe. This processed water is treated to strict standards set by the California Department of Health Services and is rigorously monitored by local, state and federal agencies to ensure it continuously meets those standards. Recycled water is safe for irrigation, industrial, and agricultural uses.
Water has naturally been recycled through the earth’s water cycle for millions of years. During the past 200 or so years what has been termed “unplanned recycling” has occurred. This consists of upstream cities discharging their treated wastewater to a river or other waterway from which downstream cities obtain water for treatment to drinking water standards. For example, the Mississippi River receives both treated wastewater and serves as a water source for many towns and cities.
During approximately the past 75 years, water agencies have constructed “planned” recycling projects where treated wastewater is used for non-potable (non-drinking) purposes. More recently, water agencies have been using advanced treatment techniques such as microfiltration, reverse osmosis, and UV disinfection to produce highly-purified (near distilled quality) recycled water for a wider range of purposes including indirect potable re-use, in which highly purified recycled water is used to recharge underground aquifers.
Benefits of recycled water:
- Conserves drinking water supplies.
- Provides a dependable, drought-proof, all-weather, and locally-controlled water supply.
- Helps restore and preserve our saltwater and tidal habitats by reducing freshwater discharge to the Bay.
- Is more economical and environmentally sustainable because it is less energy-intensive and has a lower carbon footprint than many other water supply sources (see "Watts to Water" report on the sidebar for more information about this topic)
Where does recycled water come from?
Recycled water comes from the treatment of wastewater. Wastewater is produced when we use sinks, showers, toilets, appliances and machinery in our homes, shops, offices and factories. Wastewater is piped through sanitary sewers to wastewater treatment plants where it progresses through three stages of treatment and disinfection.
The second stage of treatment is sufficient for landscape irrigation according to the California Department of Health Services. The district goes above and beyond that standard in Santa Clara County. All recycled water in Santa Clara County meets or exceeds standards set by the state for the various uses of recycled water.
Expansion of Recycled Water in Santa Clara County
To ensure an adequate and reliable supply of high-quality water, the water district has partnered with cities and water retailers in the county to develop recycled water supplies. About four percent of the county’s total water use currently consists of recycled water, limited primarily to landscaping and industrial uses.
Recycled water use is expected to expand in the coming years. Towards this end, in 2010, the district Board of Directors approved two agreements with the City of San Jose to build an Silicon Valley Advanced Water Purification Center, an advanced water treatment facility, (completed in mid-2014) that produces up to eight million gallons per day of highly purified recycled water. This highly purified water is blended into existing recycled water provided by the neighboring Santa Clara/San Jose Water Pollution Control Plant, which improves overall recycled water quality so that the water can be used for a wider variety of irrigation and industrial purposes.
Longer term, the district is investigating the possibility of using highly purified recycled water for replenishment of groundwater basins, similar to the highly successful groundwater replenishment system that has been operated by the Orange County Water District for over 30 years. However, a feasibility study, including pilot research studies, will be conducted before a decision is made regarding whether to use highly purified recycled water as a water supply option. Stakeholder and community input will be an important component of the feasibility study. The feasibility study and pilot research studies will likely be completed within 5 years; if groundwater replenishment with recycled water is selected as a water supply option, operation of such a system would likely commence 10 to 15 years from now.
For more information, contact the Santa Clara Valley Water District via e-mail or call 408-630-2449.