Mother Nature has been recycling our wastewater for millions of years through a long process of sedimentation, organic consumption, natural filtration, and disinfection. Modern technology in the wastewater industry essentially accelerates and concentrates nature’s cleansing process.

Recycled water is wastewater that has been processed through modern primary, secondary, and tertiary treatment for beneficial reuse following the strict standards of the California State Department of Public Health. According to these standards, tertiary-treated recycled water is safe for all human contact (irrigating parks and food crops, use in fountains, etc.) except drinking.

Water is a precious natural resource that is in short supply in California. Population increases and efforts to protect the environment have reduced the reliability of our water supply. Without widespread development of additional water resources, the State Department of Water Resources predicts that by the year 2020, Californians will be short 7 million acre-feet of water per year during a drought and 2.9 million acre-feet in an average year. An acre-foot of water is enough to supply two families for a year. Water reuse projects are essential to the water resources management of the region.

Water recycling, practiced for decades in the arid regions of the United States and around the world, is becoming more and more common throughout California. Dublin San Ramon Services District (DSRSD) has joined hundreds of other agencies statewide in an effort to better manage our water resources through recycling. Because it began developing a recycled water system decades ago, the District is already meeting the state mandate to reduce per capita water consumption 20 percent by 2020. Recycled water accounts for approximately 18 percent of total water sales.

State law now requires the use of recycled water if it is available and reasonably priced. Nevertheless, potential customers look forward to using recycled water for many more reasons:

Recycled water has been used throughout California as far back as the turn of the century. The founders of Golden Gate Park began irrigating with untreated sewage in 1889 to make the park soil more productive. The first water reclamation plant was constructed there in 1932. The City and County of San Francisco continue today to include water reuse in their master plan for water resources management. Meanwhile, hundreds of other water and wastewater agencies also are actively reclaiming our state’s “liquid gold.”

The District began using secondary-treated recycled water in the 1970’s to irrigate landscaping at its wastewater treatment plant. In 1977, as Interstate 580 was being built through Dublin, the District supplied up to 50,000 gallons of recycled water a day for soil compaction and dust control at freeway construction sites.

Planning for a comprehensive recycled water program with advanced tertiary treatment began here in the early 1990’s, spurred initially by the need for additional wastewater disposal capacity as well as additional water for new development included in the general plans of the cities of Dublin and San Ramon. DSRSD, the City of Livermore, and Zone 7 Water Agency conducted a recycled water study for the Tri-Valley in the early 1990’s. In 1993, the State Water Resources Control Board issued a Master Water Recycling Permit that established requirements for using recycled water in the valley.

In 1995, the District formed a joint powers authority with another neighboring agency, East Bay Municipal Utility District (EBMUD), to share the costs of building a water recycling plant and distribution network. The partnership launched the San Ramon Valley Recycled Water Program, a multi-phase project that will eventually serve DSRSD customers primarily in eastern Dublin and Dougherty Valley and EBMUD customers in San Ramon, Danville, and Blackhawk. In 1998 the partners began building the separate “purple” pipelines, pumps, and storage tanks that would deliver water to customers, as well as the microfiltration/ultraviolet (UV) disinfection system that would produce recycled water.

Deliveries began in 1999 to a small number of landscape irrigation customers, including the Dublin Sports Grounds. As the distribution network continued to expand, a higher capacity sand filtration/UV disinfection system went online at the water recycling plant in 2006. This system can supply up to 9.7 million gallons a day and is used throughout peak irrigation season, from April to October. The lower capacity microfiltration system produces up to 3 million gallons a day during the rest of the year.

New developments in DSRSD’s water service area are required by ordinance to connect to the recycled water distribution system to irrigate landscaping at parks, schools, roadway medians, and large commercial and apartment complexes. The District also is studying the feasibility of extending recycled water pipelines to older neighborhoods in central Dublin. At buildout of the Dublin and San Ramon general plans, the District plans to deliver approximately 3,700 acre-feet of recycled water annually (or 3.3 million gallons per day) in its service area.

The California State Department of Public Health (DPH) has set strict standards for recycled water use in Title 22 of the California Code of Regulations. The tertiary-treated recycled water produced by DSRSD meets standards that allow it to be used for most non-drinking purposes. In addition, DPH and the Regional Water Quality Control Boards have strict permitting procedures to ensure the reliability of treatment processes and controlled use of recycled water.

As the potential for human contact with recycled water increases, Title 22 requires a higher level of treatment and reliability. Recycled wastewater undergoes primary, secondary, and tertiary treatment at water reclamation plants. During primary treatment, large solids are removed. Secondary treatment uses bacteria to remove approximately 90 to 95 percent of the remaining solids and uses a disinfectant, such as chlorine, to destroy bacteria, viruses, and other pathogens. For many reuse applications, advanced tertiary treatment processes such as filtration or reverse osmosis are required. The treatment processes duplicate and accelerate nature’s own purifying actions.

Disinfected tertiary-treated recycled water is virtually free from all pathogens, including viruses. Several long-term microbiological studies of viruses in tertiary-treated recycled water have been conducted. These studies confirm the absence of pathogens in thousands of tertiary-treated recycled water samples. Another study completed in 2011 analyzed the trace concentrations of pharmaceuticals and personal care products (PPCPs) found in recycled water. Findings indicate that, depending on the chemical and the exposure situation, it could take anywhere from a few years to many millions of years of exposure to recycled water to reach the same exposure to PPCPs that people get in a single day through routine activities. For years, recycled water has safely been used on public facilities such as school grounds, athletic fields, golf courses, parks and common areas of residential neighborhoods. There has never been an incident suggesting even a hint of concern about the health effects of recycled water use.

Further standards have been set for recycled water that will be used for indirect potable reuse applications such as groundwater recharge. Regulation of groundwater recharge in California is under the jurisdiction of DPH and the State Water Resources Control Board in conjunction with the Regional Water Quality Control Boards. DPH has the responsibility and authority to establish public health criteria for groundwater usage. In responding to that role, DPH has established guidelines for design and operation of recycled water systems and reviews all proposals and plans for such projects throughout the state to ensure the public's health and safety.

The California State Legislature has adopted goals for water recycling that include providing for at least 1.5 million acre-feet per year of recycled water by the year 2020. Joining over 200 other water agencies throughout California, Dublin San Ramon Services District is helping to meet that goal. Recycled water is a safe and reliable resource for irrigation and other uses, and with appropriate treatment, can replenish potable water supplies such as rivers, groundwater basins,
and reservoirs.

Bay Area Water Agencies with recycled water projects include:

Many other communities across the nation have implemented projects to use purified recycled water to supplement drinking water supplies. Some communities use reverse osmosis and others use less advanced technologies. Here are
some examples: