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DSRSD laboratory technician Irene Ceballos collects a wastewater sample for observation. (Photo by Jude Strzemp) 
Dublin San Ramon Services District offers to 194,600 people services such as wastewater collection and treatment as well as the provision of recycled water and potable water. (Photo by Jude Strzemp) 
Upon entering the treatment facility, wastewater is screened of large solids such as diapers, rocks and wipes. (Photo by Jude Strzemp) 
Floating material dubbed scum is removed from wastewater during its mechanical treatment. (Photo by Jude Strzemp) 
Inside a digester, micro-organisms break down solids with a methane byproduct. (Photo by Jude Strzemp) 
A clarifier removes solid material that has settled out of wastewater. (Photo by Jude Strzemp) 
DSRSD Operations Director Dan Gill discusses the breakdown of solids in a digester at the Regional Waste Water Treatment Facility. (Photo by Jude Strzemp) 
On the recycled water side of the facility, treated wastewater undergoes disinfection by methods such as ultraviolet light. The outgoing recycled water can be used for irrigation. (Photo by Jude Strzemp)
Where one person’s business ends, another’s begins.
This is the case for the wastewater produced at the flushing of a toilet or the running of sinks and showers.
Routed from Pleasanton, Dublin and southwest San Ramon, the wastewater travels through hundreds of miles of underground pipes to the Regional Wastewater Treatment Facility in Pleasanton.
It is here that Dublin San Ramon Services District treated an average of 12.05 million gallons a wastewater daily last year to either become recycled water or for release to the San Francisco Bay.
Founded in 1953, the not-for profit public utility supports over 194,600 people with its services, which includes wastewater collection for its customers in Dublin and southwest San Ramon as well as recycled and potable water service to Dublin and Dougherty Valley. DSRSD also treats sewage from Pleasanton under a longstanding contract with the city, which owns, operates and maintains the sewer collection system within its boundaries.
Touring the site last month, the Pleasanton Weekly followed alongside DSRSD officials through the not-so-smelly process of elevating wastewater to recycled water at 7399 Johnson Drive in Pleasanton.
“It is an important part of the fabric of a society, but it is one that people don’t necessarily think about on a day-to-day basis,” DSRSD spokesperson Erin Steffen said of wastewater treatment. “It’s really when things aren’t going right that you start thinking about these things.”
DSRSD officials started the June 1 tour where wastewater processing begins — bar screening.
Located at the site’s Wastewater Treatment Plant, the escalator-like machinery pulls large solids from wastewater.
Nearby the bar screens, vacuums suck air to reduce odor in an effort that continues throughout the treatment process.
DSRSD operations director Dan Gill gestured on the tour toward rocks and wipes that were captured by the bar screens and set for disposal in landfills.
“We see all sorts of things,” Gill said, noting that they come primarily from toilets. “It’s interesting as to what ends up here.”
But only the “three Ps” should go down the toilet, Steffen explained.
Pee, poop and toilet paper.
Wipes marketed as flushable are not actually flushable, she added. The same goes for feminine hygiene products as well as fats, oils and grease.
These materials can clog the wastewater collection system and the blockages are “really messy and really expensive”, she explained.
After the bar screening, wastewater enters the stage of grit removal and pre-aeration to get rid of materials such as sand, gravel, coffee grounds and egg shells. These solids, known as grit, are also disposed of in landfills.
The wastewater then moves onto primary sedimentation tanks where floating material, known as scum, is skimmed from the surface of the water. Sinking material, or primary sludge, is also collected from the bottom of the tank for further processing.
Prior to the Clean Water Act of 1972, this was the end of the treatment process and the water was sent to the San Francisco Bay, Gill said.
But under the act, agencies are required to bring the water to a higher standard of cleanliness, he explained.
The further treatment involves biological processes in aeration bins where a mixture of yeast and single-cell organisms, such as bacteria, feed on and break down the dissolved organic matter.
Dubbed “bugs”, these critters are stressed and made to be desperate for oxygen and food, Steffen explained.
“Then we introduce them to this area and we’re giving them all the oxygen and all the bacteria,” Steffen said. “It’s like a Thanksgiving feast and they haven’t eaten for a day.”
Next up is a secondary sedimentation tank or clarifier for additional sludge removal, followed by disinfection at the site’s Jeffrey G. Hansen Water Recycling Plant.
The disinfected liquid is then sent on one of two routes.
About 60% of it is sent annually to the East Bay Dischargers Authority System to be de-chlorinated and released to the San Francisco Bay.
The remaining disinfected wastewater is routed to the recycled water treatment plant on-site. But on summer days, up to 100% of the treated wastewater is routed to become recycled water for uses such as irrigation.
Last year, DSRSD produced 1.4 billion gallons of recycled water, according to Steffen.
“Recycled water is a big piece of how we are conserving our drinking water for its intended purpose,” Steffen said.
Looking toward the future, Gill said DSRSD may need to upgrade its plant with nutrient removal methods for discharging treated wastewater to the Bay.
High nutrient discharge to the Bay plays a role in algae blooms and regulations are currently in place to limit the nutrients released by any agency, he explained.
“Our recycled water operation is a huge component of diverting those nutrients from the San Francisco Bay to our irrigation customers,” Gill said. “It’s doing two jobs. We’re meeting our conservation goals and we’re also meeting our goals to reduce our impact on the environment.”
Steering the tour to its Biosolids Facility, DSRSD officials showed the Weekly a sludge thickener where water is removed from sludge that was previously separated from wastewater by the primary and secondary sedimentation tanks.
The sludge is later sent to a mechanical digester, likened to a stomach, where the material is broken down and methane is released as a byproduct.
Bio-solids output from digesters are moved to facultative sludge lagoons located across Stoneridge Drive.
Every three years the solids are pumped out and moved to an adjacent land disposal area. A natural process occurs that elevates the bio-solids to Class A standards for potential use in farming, but DSRSD does not sell the material because it would not be cost effective, Steffen explained.
As for the methane by-product of digestion, co-generation engines use that gas to cover 95% of the wastewater treatment plant’s electricity needs, Gill said.
However, DSRSD is at its co-generation capacity, meaning some excess methane is produced and burned, according to Gill.
The agency is currently in the design process for scaling up its co-generation ability and expects the associated investment to cost tens of millions of dollars.
The utility exists at the intersection of environmental protection, public health and conservation, Steffen said.
“We think of ourselves as more of a resource recovery facility,” she added. “We are taking these products and byproducts of the wastewater treatment process and we are utilizing those to benefit either the environment, to have a neutral impact on the environment or to help to provide the heat or energy that’s necessary for the work that takes place here.”
DSRSD enters fiscal year 2026-27 with an operating budget of $83.02 million. In the coming months, the agency is set to have two seats open on its elected Board of Directors.
The Division 2 seat, representing southwest San Ramon, and Division 4, representing central Dublin, will be up for a vote in the November general election. Interested residents who live within those boundaries can file their candidacy papers with DSRSD until Aug. 7.
Elsewhere in the Tri-Valley, Livermore has its own wastewater reclamation plant at 101 W. Jack London Blvd.
The city has been anticipating for years the South Livermore sewer extension project to expand sewer services to properties along Buena Vista Avenue between East Avenue and Tesla Road, down Tesla Road and along part of Greenville Road.
The $15 million project, funded by Alameda County, is meant to protect groundwater from contamination and support the wine country.
Otherwise, wastewater customers in the Tri-Valley north of the DSRSD jurisdiction – the rest of San Ramon and all of Danville and Alamo – all the way toward Martinez receive wastewater and collection services from the Central Contra Costa Sanitary District. Known by its short-hand Central San, the public utility celebrated its 80th anniversary of service this year.
