California Wastewater Treatment Plants

California Wastewater Treatment Plants

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Read moreA Comparison Between Aerobic And Anaerobic Wastewater Treatment Technology

1. Introduction

California represents the largest and most complex wastewater market in the United States. Driven by chronic water scarcity, seismic risks, and stringent environmental regulations, the state’s infrastructure is undergoing a massive paradigm shift from “waste disposal” to “resource recovery.” California operates approximately 900 active wastewater treatment facilities, managing a total design capacity exceeding 4.5 billion gallons per day (BGD).

The engineering landscape is defined by the mandates of the State Water Resources Control Board (SWRCB) and nine Regional Water Quality Control Boards. Currently, the state is investing heavily in Potable Reuse (IPR and DPR) projects, nutrient removal upgrades for the San Francisco Bay, and biosolids modernization. For consulting engineers and equipment vendors, California offers the highest density of large-scale capital improvement projects in the nation, with a clear trajectory toward closed-loop water cycles and carbon-neutral operations.

2. Recent Developments & Projects

In the last 36 months, California’s wastewater sector has pivoted aggressively toward Advanced Water Purification (AWP). The defining development is the “Pure Water” movement, with multi-billion dollar programs active in San Diego, Los Angeles, and Santa Clara counties. These projects utilize Full Advanced Treatment (FAT)—typically Microfiltration, Reverse Osmosis, and UV/Advanced Oxidation—to generate potable water supplies.

Significant funding has been mobilized through the Clean Water State Revolving Fund (CWSRF) and the federal Water Infrastructure Finance and Innovation Act (WIFIA). Notably, the EPA has issued master loans exceeding $1.5 billion to support these water resilience projects. Furthermore, the San Francisco Bay Area is grappling with the new Nutrient Watershed Permit, driving upgrades at over 30 facilities to reduce nitrogen loads, a major shift for plants that historically relied on tidal dispersion.

3. Top 20 Largest Treatment Plants

The following list ranks California’s wastewater treatment plants by Design Average Dry Weather Flow (ADWF) capacity. These facilities represent the backbone of the state’s sanitary infrastructure.

Rank Plant Name City/Location Design Capacity (MGD) Population Served Operating Authority
1 Hyperion Water Reclamation Plant Playa del Rey 450 MGD 4.0 Million City of Los Angeles (LASAN)
2 Joint Water Pollution Control Plant Carson 400 MGD 3.5 Million LA County Sanitation Districts
3 Point Loma Wastewater Treatment Plant San Diego 240 MGD 2.2 Million City of San Diego
4 Main Wastewater Treatment Plant Oakland 168 MGD 740,000 EBMUD
5 Plant No. 2 Huntington Beach 150 MGD 1.5 Million Orange County Sanitation District
6 Sacramento Regional Wastewater Treatment Plant Elk Grove 181 MGD 1.6 Million Regional San
7 San Jose-Santa Clara Regional Wastewater Facility San Jose 167 MGD 1.4 Million City of San Jose
8 Plant No. 1 Fountain Valley 130 MGD 1.1 Million Orange County Sanitation District
9 Southeast Treatment Plant San Francisco 85 MGD 550,000 SFPUC
10 Michelson Water Recycling Plant Irvine 28 MGD* 450,000 Irvine Ranch Water District
11 Tillman Water Reclamation Plant Van Nuys 80 MGD 800,000 City of Los Angeles (LASAN)
12 Fresno-Clovis Regional WRF Fresno 80 MGD 750,000 City of Fresno
13 Inland Empire Regional Water Recycling Plant No. 1 Ontario 44 MGD 850,000 IEUA
14 Alvarado Wastewater Treatment Plant Union City 33 MGD 346,000 Union Sanitary District
15 Encina Water Pollution Control Facility Carlsbad 40 MGD 380,000 Encina Wastewater Authority
16 San Jose Creek Water Reclamation Plant Whittier 100 MGD 1.0 Million LA County Sanitation Districts
17 Oxnard Wastewater Treatment Plant Oxnard 31.7 MGD 250,000 City of Oxnard
18 Hale Avenue Resource Recovery Facility Escondido 18 MGD 150,000 City of Escondido
19 Terminal Island Water Reclamation Plant San Pedro 30 MGD 130,000 City of Los Angeles (LASAN)
20 Palo Alto Regional Water Quality Control Plant Palo Alto 39 MGD 220,000 City of Palo Alto

*Note: Capacities listed are Average Dry Weather Flow design limits. Wet weather peak capacities are significantly higher.

Detailed Profiles of the Top 5 Largest Plants

1. Hyperion Water Reclamation Plant

  • Location: Playa del Rey, Los Angeles County

  • Design Capacity: 450 MGD (850 MGD Peak Wet Weather)

  • Operating Authority: LA Sanitation & Environment (LASAN)

  • Receiving Water: Pacific Ocean (via 5-mile outfall)

  • Treatment Process: Advanced Secondary (High-purity oxygen activated sludge). Future: 100% recycling via MBR/RO/UV.

  • Infrastructure: Uses the Cryogenic Air Separation process for oxygen generation. Handles biosolids via thermophilic digestion; Class A biosolids used for land application.

  • Key Upgrade: Operation NEXT. This initiative aims to recycle 100% of Hyperion’s effluent by 2035, necessitating a massive retrofit to MBR and RO technologies.

2. Joint Water Pollution Control Plant (JWPCP)

  • Location: Carson, Los Angeles County

  • Design Capacity: 400 MGD

  • Operating Authority: Los Angeles County Sanitation Districts (LACSD)

  • Receiving Water: Pacific Ocean

  • Treatment Process: Advanced Primary and Secondary Treatment (High purity oxygen activated sludge).

  • Infrastructure: Features a massive Total Energy Facility that generates roughly 20MW of power from digester gas.

  • Key Upgrade: Pure Water Southern California. A partnership with Metropolitan Water District to construct a 150 MGD advanced purification facility on-site.

3. Point Loma Wastewater Treatment Plant

  • Location: San Diego, San Diego County

  • Design Capacity: 240 MGD

  • Operating Authority: City of San Diego Public Utilities

  • Receiving Water: Pacific Ocean

  • Treatment Process: Advanced Primary Treatment (Chemically Enhanced Primary Treatment).

  • Compliance Note: Operates under a modified NPDES permit (301(h) waiver). The city is moving toward diverting flow upstream to Pure Water facilities to reduce ocean discharge.

  • Infrastructure: Uses hydroelectric generation on the outfall drop structure.

4. Main Wastewater Treatment Plant (EBMUD)

  • Location: Oakland, Alameda County

  • Design Capacity: 168 MGD (Average), 415 MGD (Peak Secondary)

  • Operating Authority: East Bay Municipal Utility District

  • Receiving Water: San Francisco Bay

  • Treatment Process: High-purity oxygen activated sludge.

  • Recent Feature: EBMUD is a pioneer in “Resource Recovery,” accepting trucked organic waste (FOG/food scraps) to co-digest and generate excess renewable energy, making the plant net-energy positive.

5. Orange County Sanitation District Plant No. 2

  • Location: Huntington Beach, Orange County

  • Design Capacity: 150 MGD

  • Operating Authority: OC San

  • Receiving Water: Pacific Ocean

  • Treatment Process: Activated Sludge / Trickling Filters.

  • Key Feature: Works in tandem with Plant No. 1 to feed the Groundwater Replenishment System (GWRS), the world’s largest water purification system for indirect potable reuse.

4. Plants with Approved Budgets & Expansion Projects

California currently leads the nation in capital expenditure for wastewater infrastructure. Below is a detailed breakdown of active major projects.

A. Major Projects Under Construction (2024-2026)

Pure Water San Diego – Phase 1

  • Location: San Diego

  • Total Budget: $1.5 Billion (Phase 1)

  • Scope: Construction of the North City Pure Water Facility (30 MGD), pump stations, and pipelines. Diverts wastewater from Point Loma WWTP for purification.

  • Funding: $614M WIFIA Loan, SRF Loans, Bureau of Reclamation Title XVI Grants.

  • Timeline: Construction active; Completion expected 2025.

  • Key Contractors: Parsons, Black & Veatch (Design), Shimmick Construction.

  • Technology: Ozonation, Biological Activated Carbon (BAC), MF, RO, UV/AOP.

SFPUC Biosolids Digester Facilities Project (BDFP)

  • Location: Southeast Treatment Plant, San Francisco

  • Total Budget: $3.3 Billion

  • Scope: Complete replacement of aging digesters with new Class A biosolids facilities using Thermal Hydrolysis Process (THP).

  • Timeline: Construction active; Completion expected 2028.

  • Drivers: Seismic safety, odor control, and regulatory compliance.

  • Technology: Cambi Thermal Hydrolysis, advanced odor control scrubbers.

Silicon Valley Clean Water (SVCW) RESCU Program

  • Location: Redwood City

  • Total Budget: $955 Million

  • Scope: Gravity Pipeline tunnel replacement, new Front of Plant lift station, and pump station rehabilitation.

  • Timeline: Major tunneling complete 2023; Final rehabilitation ongoing through 2025.

  • Funding: Progressive Design-Build delivery model.

B. Projects in Design/Planning Phase (2025-2027)

Pure Water Southern California (Regional Recycled Water Program)

  • Location: Carson (JWPCP)

  • Estimated Budget: $4.0 – $6.0 Billion

  • Status: Environmental Planning / Preliminary Design.

  • Scope: A 150 MGD Advanced Water Purification facility. Will represent one of the largest reuse projects in the world.

  • Partnership: Metropolitan Water District and LACSD.

Hyperion 2035 (Operation NEXT)

  • Location: Los Angeles

  • Estimated Budget: $3.0+ Billion

  • Status: Program Management / Pilot Phase.

  • Scope: Conversion of the 450 MGD Hyperion plant to 100% water recycling using MBR and RO.

C. Recently Completed Major Projects (2022-2024)

  • EchoWater Project (Sacramento Regional San): Completed in 2023. A $1.7 billion massive upgrade to tertiary treatment for biological nutrient removal (BNR) to protect the Delta.

  • GWRS Final Expansion (Orange County): Completed in 2023. Increased capacity from 100 MGD to 130 MGD, recycling 100% of OC San’s reclaimable wastewater flows.

Summary Statistics: California Capital Investment

  • Total Active Capital Investment: >$12 Billion currently programmed.

  • Primary Drivers: Water Reuse (60%), Aging Infrastructure/Seismic (25%), Nutrient Removal (15%).

  • Dominant Funding Sources: WIFIA Loans and State Revolving Fund (SRF).

  • New Reuse Capacity: Over 400 MGD planned by 2035.

5. Regulatory & Compliance Landscape

California operates under the Porter-Cologne Water Quality Control Act, which often sets standards stricter than the federal Clean Water Act.

Key Regulations for Engineers:

  • Title 22 (California Code of Regulations): The gold standard for water recycling criteria. Recent amendments now include frameworks for Direct Potable Reuse (DPR), adopted by the SWRCB in late 2023, allowing treated wastewater to be introduced directly into potable water distribution systems without an environmental buffer.

  • San Francisco Bay Nutrient Watershed Permit: Requires 30+ dischargers in the Bay Area to reduce nutrient loads (Nitrogen/Phosphorus) significantly by 2029 to prevent algal blooms.

  • PFAS/PFOA Monitoring: The SWRCB has issued investigative orders requiring testing for PFAS at wastewater facilities. Future NPDES permits are expected to include effluent limits for these “forever chemicals.”

  • Biosolids (SB 1383): This legislation targets methane reduction and mandates the diversion of organic waste from landfills, pushing WWTPs to accept food waste for co-digestion.

7. Technology Trends in California

Due to the high cost of water and energy, California facilities are early adopters of advanced technologies:

  • Membrane Bioreactors (MBR): Becoming the standard for new reuse facilities due to high effluent quality and smaller footprints (e.g., Hyperion retrofit plans).

  • UV/Advanced Oxidation (AOP): Essential for destruction of micro-constituents and pathogens in potable reuse trains.

  • Thermal Hydrolysis (THP): Being deployed at SFPUC and planned for other major metros to maximize biogas production and reduce Class A biosolids volume.

  • Ceramic Membranes: Gaining traction in pilot projects for their durability in tough water matrices.

8. Directory of Facilities

Browse our organized directory of water and wastewater treatment plants in California:

Major Regional Facilities (>100 MGD)

  • Hyperion Water Reclamation Plant (Los Angeles)

  • Joint Water Pollution Control Plant (Carson)

  • Point Loma Wastewater Treatment Plant (San Diego)

  • Sacramento Regional Wastewater Treatment Plant (Elk Grove)

  • EBMUD Main Wastewater Treatment Plant (Oakland)

  • OC San Plant No. 1 & No. 2 (Orange County)

Large Municipal Plants (50-100 MGD)

  • Southeast Treatment Plant (San Francisco)

  • Tillman Water Reclamation Plant (Van Nuys)

  • San Jose Creek Water Reclamation Plant (Whittier)

  • Fresno-Clovis Regional WRF (Fresno)

(Full directory available in our searchable database)

9. Resources for Engineers & Operators

  • CWEA (California Water Environment Association): The primary body for operator certification and technical conferences. Visit CWEA.

  • SWRCB Division of Financial Assistance: Managing agency for SRF loans and grants.

  • CASA (California Association of Sanitation Agencies): Represents legislative interests of wastewater agencies.

10. FAQ

How many wastewater treatment plants are in California?

There are approximately 900 active wastewater treatment facilities in California, ranging from small package plants to massive regional facilities treating over 400 MGD.

What is the largest wastewater treatment plant in California?

The Hyperion Water Reclamation Plant in Los Angeles is the largest, with a design capacity of 450 MGD and peak wet weather capacity of 850 MGD.

What is the “Pure Water” initiative?

“Pure Water” refers to a series of programs (San Diego, LA, SoCal) that use advanced purification technologies (Ozonation, MF, RO, UV/AOP) to recycle wastewater into potable water supplies, reducing reliance on imported water.

Are there funding opportunities for wastewater projects in California?

Yes. The primary source is the Clean Water State Revolving Fund (CWSRF). Additionally, the EPA’s WIFIA program has been heavily utilized by California agencies for large-scale infrastructure projects.

What are the operator certification requirements in California?

Wastewater treatment plant operators must be certified by the State Water Resources Control Board (SWRCB). There are five grades of certification (Grade I through V), requiring increasing levels of education and experience.