Recycled Water General Information

Los Angeles has long relied on water imported from hundreds of miles away to support its water demands, but environmental programs, court rulings, periods of dry weather and low snowpack, and climate change have threatened the reliability of these imported supplies. The City's water supply comes from:

• Imported water from Owens Valley and Mono Lake Basin (Los Angeles Aqueduct);
• Purchased water from the Metropolitan Water District of Southern California (MWD), which is imported from Northern California (California Aqueduct) and the Colorado River (Colorado River Aqueduct); and
• Several local water sources including groundwater, captured stormwater, and recycled water, which are safe and more reliable than imported water supplies.

The City is planning Los Angeles' water future in order to increase reliability. By increasing our local water supplies, such as recycled water, we can reduce our dependence on imported water. Locally, the City treats over 450,000 acre-feet per year (AFY) of wastewater, most of which is discharged into the ocean. The City aims to produce over 65,000 AFY by 2045 for municipal and industrial uses, groundwater replenishment, and environmental uses. In addition, by planning into the future, beyond 2035, the City can find ways to utilize the remaining treated wastewater before it is discharged into the ocean.

Definition of Recycled Water

Recycled water (also called reclaimed water and water reuse) is highly treated wastewater that has gone through multiple levels of treatment that makes it safe for beneficial uses. Recycled water must be closely monitored and tested to ensure that it meets stringent health and safety standards set by the California Department of Public Health (CDPH) and enforced by nine state Regional Water Quality Control Boards (RWQCB).

Recycled water has been used for non-potable reuse applications in many parts of the United States, including Los Angeles, for decades. Municipal wastewater that has completed tertiary treatment can be used to irrigate schoolyards, parks, and residential landscape and may be suitable for industrial application such as cooling towers. Other examples of non-potable reuse include agricultural irrigation, dust control during construction, and habitat restoration.

Recycled water for groundwater replenishment applications has a long history in the Los Angeles region. One of the most well-known programs world-wide is operated by the Orange County Water District / Orange County Sanitation District. The City of Los Angeles has its own program, producing highly treated recycled water at the Terminal Island Water Reclamation Plant and injecting about 5,000 acre-feet in FY 23-24 of purified water into the Dominguez Gap Barrier to protect drinking water in the aquifer from seawater intrusion. Additionally, the Los Angeles Groundwater Replenishment Project at Donald C. Tillman Water Reclamation Plant will produce advanced purified water to improve groundwater recharge in the San Fernando Basin.

Commitment to Water Recycling

In Los Angeles, recycled water is currently produced at three water reclamation facilities owned by the City and operated by the City of Los Angeles Department of Public Works, Bureau of Sanitation and Environment (LASAN):

1. Donald C. Tillman Water Reclamation Plant (DCTWRP)
2. Los Angeles-Glendale Water Reclamation Plant (LAGWRP)
3. Terminal Island Water Reclamation Plant.

Secondary treated water is produced at the Hyperion Water Reclamation Plant (HWRP) and is provided to the West Basin Municipal Water District (WBMWD) for further treatment. The City uses tertiary water from the WBMWD for beneficial reuse.

LADWP's recycled water service area is grouped into four main service areas: Harbor, Metro, Valley, and the Westside. The existing distribution system has 70 miles of pipeline, two water tanks, and three pumping stations. Existing recycled water infrastructure delivered approximately 10,000 acre-feet to recycled water customers for irrigation and industrial uses as well as an additional 22,740 acre-feet for environmental uses in FY 23-24.

LADWP is currently planning, designing, or constructing expansions of recycled water infrastructure that will deliver about an additional 35,000 AFY for indirect potable reuse, industrial applications, and seawater intrusion protection. Together this infrastructure – in place or in progress – will provide over 65,000 AFY by 2035 of recycled water for beneficial uses.

How Water is Recycled

Recycled water is produced by treating wastewater that involves processes that, at minimum, remove solids to a level that meets regulatory water quality standards. The treatment processes include preliminary, primary, secondary, and tertiary treatments, each of which removes progressively finer grains of solids. At the end of secondary treatment, most solids have been removed from the water. Tertiary treatment eliminates any remaining impurities through filtration and disinfection. All recycled water in the city undergoes tertiary treatment. Advanced treated water will also be produced at the Donald C. Tillman Water Reclamation Plant upon completion of the Los Angeles Groundwater Replenishment Project. Advanced treated water receives additional microfiltration, reverse osmosis and UV-Advanced Oxidation Process (UVAOP) and is produced at the LADWP Terminal Island Water Reclamation Plant.

Approved Uses of Recycled Water

Recycled water is defined under the California Code of Regulations, also known as Title 22, which allows it to be used on food crops, parks, playgrounds, school yards, residential landscaping, cemeteries, freeway landscaping, golf courses, ornamental nurseries, animal pastures, orchards, and vineyards. In addition, recycled water can be used for fishing or environmental benefits, fish hatcheries, cooling towers, and decorative fountains.

How Recycled Water is Used in Los Angeles

Recycled water treated to a secondary, or tertiary level, is used primarily for irrigation and industrial purposes, notably to irrigate golf courses, parks, cemeteries, and in cooling towers such as at Valley Generation Station. The application of recycled water is dependent on the level of treatment. In the Los Angeles Harbor area, advanced treated water utilizing microfiltration and reverse osmosis is used to protect against seawater intrusion. In the Los Angeles Valley area, once the LA Groundwater Replenishment Project is complete, highly purified recycled water will be used for groundwater replenishment.