About the Plant

CPA CleanBay Stats Slider Draft [10.08.24] - 1140 x 440_A.png

The Regional Water Quality Control Plant treats 20 million gallons of sewage per day from 236,000 residents and businesses in its service area. Located on 25 acres near the Baylands Nature Preserve, the Plant serves as a regional plant for six partner agencies (East Palo Alto Sanitary District, Los Altos, Los Altos Hills, Mountain View, Palo Alto, and Stanford University).

First built in 1934, the Plant has expanded and upgraded over the decades. The treatment process now uses a combination of physical, biological, and chemical processes to remove pollutants. When the treatment process is complete, 99 percent of the solids and organic materials have been removed from the wastewater.

What happens after I flush?

Treating raw sewage is essential to protecting human health and our environment. It goes through several steps to remove pollutants. It starts with physical processes to remove solids. Then microorganisms are employed to eat organic matter through two different treatment processes. The water is then clarified by allowing microorganisms to settle out of the water and then filtered. Lastly, it is disinfected with either ultraviolet light (UV) if it will be released to the Bay or chlorine if it is to be used as recycled water. An onsite laboratory provides quality assurance at each step. The whole process takes approximately 21 hours.

The treated wastewater may flow into the San Francisco Bay, the Emily Renzel Wetlands and Pond, the Horizontal Levee, or be used as recycled water. Sludge is a leftover byproduct of the process, and it is dried in our sludge dewatering and loadout facility. Trucks transport it off-site so it can be further processed into biosolids to be reused as fertilizer.

Take a video tour of the Plant's wastewater treatment process.

Take a Tour of the Plant

See how operators, scientists, and engineers work together to keep the treatment plant operating 24 hours a day, seven days a week. Tours are offered on Monday, Tuesday, and Wednesday with an appointment to the public. Youth must be 6th grade or higher. School groups are welcome.

Review the Plant Tour Guidelines prior to requesting a tour.

Questions? Please call (650) 329-2598 or email CleanBay@PaloAlto.gov

Schedule a free tour

Regional Collaborations

There are 37 wastewater treatment plants that discharge into the San Francisco Bay. Because of their shared environmental responsibility, regional collaborations are necessary to collectively study and protect the Bay from pollution. The Plant and the City’s Watershed Protection group collaborates with many organizations. It also funds a selection of nonprofit organizations that further pollution prevention goals. Collaborative efforts include:

studying wastewater
improving wastewater treatment
providing public outreach to encourage pollution prevention
influencing regulations as needed

Significant partners include, but are not limited to:

Laboratory

Lab team.jpg

The Plant’s laboratory plays a key role in keeping Palo Alto’s water clean and safe. Staff perform tests to ensure the wastewater treatment plant meets permit requirements set by the National Pollutant Discharge Elimination System (NPDES). Testing procedures meet all state and federal standards for wastewater, sludge, and drinking water.

The laboratory is certified by the Environmental Laboratory Accreditation Program (ELAP) to analyze a variety of substances, including organic and inorganic chemicals, toxic elements, and microorganisms. Testing follows strict methods like Standard Methods, Environmental Protection Agency (EPA) guidelines, and those in the Code of Federal Regulations (CFR): Title 40, Chapter 1, Subchapter D, Part 136 – Guidelines Establishing Test Procedures for the Analysis of Pollutants.

The laboratory team includes two Grade IV analysts certified by the California Water Environment Association (CWEA), three technicians, three chemists, two senior chemists, and a lab manager. Together, they uphold the highest standards of water quality.

Certificate of Environmental Laboratory Accreditation.pdf(PDF, 179KB)

Fields of Accreditation for Certificate of Environmental Laboratory Accreditation.pdf(PDF, 54KB)

Pollution Prevention in Wastewater

The Plant and the City’s Watershed Protection group work together to prevent pollution to the creeks and San Francisco Bay. If needed, they also advocate for regulations to reduce or eliminate harmful pollutants found in wastewater. Over the years, this work has led to significant environmental achievements which are detailed in the Plant’s Pollution Prevention Report, Clean Bay Plan 2025.

Contaminants of Concern

Through a combination of public outreach and regulation, the Plant works to prevent pollutants from reaching the sewer system and eventually the Bay. There are many classic contaminants in wastewater (metals, fats, oils and grease) but there are also contaminants of emerging concern (CECs). These are chemicals that have been found in the Bay that may cause ecological and human health impacts but are not currently regulated. Examples of CECs are pharmaceuticals, personal care products, pesticides, microplastics, and per- or polyfluoryoalkyl substances (PFAS). The Plant also tracks and participates in regional monitoring programs to identify CECs and their source. It then works on regulations or outreach programs to reduce or eliminate them in wastewater.

Per- or polyfluoryoalkyl substances (PFAS)

What are PFAS?

PFAS are a family of chemicals found in consumer and industrial products, including non-stick coatings, waterproofing materials, and manufacturing additives. PFAS are known as “forever chemicals” because they are highly persistent and take years to degrade naturally in the environment. Scientific studies have shown that exposure to PFAS chemicals is linked to harmful health effects in humans and animals. Studies focused on the Bay’s wildlife, including fish, bird eggs, and harbor seals, indicate concerning PFAS levels that may pose a risk to the Bay’s ecosystem health.

Visit Baywise.org to learn more about PFAS and how to prevent them

Regional studies

Evidence from regional studies indicate that PFAS chemicals are not removed during the wastewater treatment system process and can pass through to wastewater effluent and biosolids. In 2020, the Plant was selected as one of 14 Bay Area treatment plants to provide samples for a PFAS study conducted by the San Francisco Estuary Institute Regional Monitoring Program. This research helped inform future monitoring strategies and showed that PFAS levels are comparable across the participating treatment plants. Currently, there are no limits for PFAS levels in wastewater effluent. However, PFAS concentrations in municipal wastewater effluent are significantly lower compared to other industrial operations.

The Plant is planning a future survey to identify potential industrial sources of PFAS in its service area. The goal is to identify PFAS pollution prevention measures. One such effort was completed in 2022: the City’s identification and removal of PFAS-containing firefighting foams used by the Palo Alto Fire Department. The Plant will also continue to work with partner agencies to track and support state legislation restricting the use of PFAS in consumer and industrial products.

BACWA Regional PFAS efforts

PFAS in Biosolids

Because biosolids are used as an agricultural soil amendment, PFAS in them are an emerging concern. Many states have set PFAS limits for biosolids that either ban their use as a fertilizer or require additional source control. California currently has no PFAS limits for biosolids. However, PFAS levels monitored in the Plant's biosolids are below the lowest limits set by Michigan, New York, Wisconsin, and Colorado. The Long Range Facilities Plan Update will include a biosolids disposal plan that evaluates the impact of evolving future regulations on emerging contaminants of concern, including PFAS.

This map illustrates actions that states are taking to study or limit PFAS in biosolids.

Nutrient Reduction in Wastewater

Wastewater treatment plants are one source of nutrients to the San Francisco Bay. Nitrogen and phosphorus are the two main nutrients found in wastewater. They come from sources like human waste, food scraps, and soaps and detergents.

Nutrients are essential for life. However an excess of nutrients can contribute to the harmful overgrowth of algae, known as algal blooms, which can kill fish. Two such algal blooms occurred in 2022 and 2023 and led to increasingly more stringent regulations for discharging nutrients to the Bay. The Plant is upgrading its Secondary Treatment Process to reduce nutrient loading in the Bay.

Contact Us

Email

cleanbay@paloalto.gov

Phone

(650) 329-2598

Address

2501 Embarcadero Way

Palo Alto, CA 94303