Inside the operation of the Donald C. Tillman Water Reclamation Plant
The Donald C. Tillman Water Reclamation Plant is one of the San Fernando Valley’s most important pieces of water infrastructure. Located in Van Nuys, the facility treats municipal wastewater and converts it into a reliable source of reclaimed water for nonpotable uses. Its work is easy to overlook because most of the process happens behind the scenes, yet the plant operates continuously to protect public health and support regional water resilience.
With a rated capacity of approximately 80 million gallons per day, Tillman is designed for a demanding urban service area. Wastewater arrives from homes, businesses, and institutions carrying organic matter, suspended solids, nutrients, and other pollutants. A carefully sequenced treatment process removes those contaminants before the water is disinfected and made available for reuse or environmentally responsible discharge.
The plant also demonstrates how engineering, operations, maintenance, laboratory testing, and public communication must work together. Its performance depends on pumps, basins, clarifiers, filters, electrical systems, control software, and trained personnel functioning as one coordinated system.
From collection system to treatment facility
Wastewater begins its journey in a network of sewers that collect flows from across the surrounding community. By the time it reaches the reclamation plant, operators must manage changing volumes and compositions. Morning and evening peaks, rainfall, commercial discharges, and seasonal patterns can all influence the characteristics of the incoming flow.
The first responsibility is to protect downstream equipment. Bar screens remove large debris, while grit removal systems capture sand, gravel, and other dense material that could damage pumps or settle in process tanks. These early steps may appear simple, but reliable headworks operation is essential. A blocked screen or poorly functioning grit system can create problems throughout the facility.
Flow measurement and sampling begin early in the process. Operators use this information to understand loading conditions and adjust equipment as needed. The objective is steady treatment, even when the incoming wastewater changes from hour to hour.
How the treatment train removes pollutants
After preliminary treatment, wastewater passes through primary treatment, where settling separates a portion of the heavier solids from the liquid stream. Scrapers collect settled material, while floating grease and scum are removed from the surface. This stage reduces the burden placed on the biological process that follows.
The central treatment step uses microorganisms to consume dissolved and suspended organic material. In aeration basins, operators provide oxygen and maintain conditions that allow microbial communities to thrive. These organisms convert biodegradable pollutants into biological solids and more stable compounds. Air delivery must be carefully controlled: too little oxygen can limit treatment performance, while too much can waste energy.
Secondary clarifiers then separate the biological solids from the treated liquid. Some settled biomass is returned to the aeration basins to maintain the process population. Excess solids are removed for further handling. The clarified water advances to additional treatment, while operators monitor settling behavior, sludge concentration, dissolved oxygen, and other indicators of biological health.
The final polishing stages
Tertiary treatment gives the reclaimed water an additional level of polishing. Filtration removes fine particles that remain after biological treatment and clarification. Depending on the operating configuration, filters may use granular media or other technologies that capture small suspended materials and improve water clarity.
Disinfection is the final barrier before the reclaimed water enters its designated reuse or discharge pathway. Chlorination has historically been a key part of wastewater disinfection, with contact time and residual levels carefully managed. Operators verify that treatment meets regulatory requirements through routine sampling, laboratory analysis, and continuous process monitoring.
| Treatment stage | Primary purpose | Typical operational focus |
|---|---|---|
| Screening and grit removal | Protect equipment and remove coarse material | Screen cleaning, grit collection, pump protection |
| Primary settling | Separate heavier solids and scum | Sludge withdrawal, scraper performance, hydraulic balance |
| Biological treatment | Reduce organic pollutants through microbial activity | Aeration, dissolved oxygen, return activated sludge |
| Secondary clarification | Separate biological solids from treated water | Settling rates, blanket levels, solids management |
| Filtration and disinfection | Polish and disinfect the reclaimed water | Filter performance, chlorine contact, compliance sampling |
| Solids handling | Stabilize and manage removed solids | Thickening, digestion, dewatering, beneficial disposition |
The treatment train is supported by alarms, analyzers, programmable controls, and supervisory systems. Automation helps operators identify changing conditions quickly, but it does not replace professional judgment. Field inspections and process knowledge remain essential when equipment behaves unexpectedly or data does not match conditions on the ground.
Reclaimed water supports the surrounding community
Water reclamation extends the value of every gallon that enters the facility. Once treated to the required standard, reclaimed water can serve approved nonpotable purposes such as landscape irrigation, industrial applications, and other local demands. Using recycled water for these purposes reduces pressure on imported and local drinking-water supplies.
The plant is closely associated with the Japanese Garden, a public landscape built around reclaimed water infrastructure. The garden offers visitors a visible example of how a highly engineered treatment process can support an attractive community space. Nearby Lake Balboa and other landscaped areas also help connect water recycling with everyday urban life.
This public-facing dimension matters. Water treatment plants are often perceived only as utility assets, but facilities such as Tillman show how infrastructure can be integrated into a neighborhood. Clear communication about treatment standards, permitted uses, monitoring, and environmental safeguards helps build public confidence in recycled water programs.
Professionals can learn more about technical tours, workshops, and networking opportunities through upcoming events offered by LABS of CWEA. These programs create a setting where plant operations can be discussed alongside the broader challenges facing Southern California water management.
People make continuous operation possible
A reclamation plant runs around the clock, including weekends and holidays. Operations staff inspect tanks, check pumps, respond to alarms, collect samples, and coordinate maintenance. Instrumentation and electrical specialists keep essential controls functioning, while mechanics and technicians maintain rotating equipment, valves, blowers, conveyors, and other assets.
Laboratory personnel provide another critical layer of assurance. Treatment decisions depend on timely measurements of flow, solids, oxygen demand, disinfectant residual, and other water-quality parameters. Results help confirm compliance and reveal trends before they become operational problems.
Safety is woven into every task. Confined-space entry, chemical handling, electrical work, biological exposure, moving machinery, and vehicle traffic all require formal procedures and ongoing training. A strong safety culture protects employees while supporting dependable service.
Leadership continuity also benefits the profession. The LABS of CWEA presidents reflect the experience and service that have helped guide water and wastewater professionals across the Los Angeles Basin. That institutional memory reinforces the importance of mentoring, knowledge transfer, and participation in professional organizations.
Operational lessons from a complex facility
A modern reclamation plant is best understood as a living system rather than a collection of isolated machines. Hydraulic conditions affect biological treatment; biological performance affects clarification; clarification affects filtration; and filtration affects disinfection. Small changes early in the process can influence final water quality many hours later.
The facility also illustrates why resilience requires planning beyond normal operation. Backup power, redundant equipment, preventive maintenance, spare parts, emergency response procedures, cybersecurity, and trained staff all contribute to continuity. Climate variability and tighter water-quality expectations make this kind of preparedness increasingly important.
For engineers, operators, consultants, and agency staff, a visit to a large treatment plant can translate technical concepts into practical understanding. Useful observations include:
- Trace the flow path from headworks to final disinfection and identify where each contaminant is addressed.
- Compare automated readings with field conditions during inspections and rounds.
- Examine how maintenance access, equipment redundancy, and safety controls influence reliability.
- Connect laboratory results with operational adjustments in aeration, clarification, filtration, or disinfection.
- Consider how reclaimed-water customers and nearby residents experience the facility.
The Donald C. Tillman Water Reclamation Plant represents the scale, discipline, and collaboration required to manage urban wastewater responsibly. Its treatment basins and control systems are important, but so are the people who interpret data, maintain assets, protect one another, and explain the value of water reuse. Explore LABS of CWEA’s professional community and take part in the conversations, tours, and training that keep the water environment profession moving forward.