2025 Drinking Water Quality Report Summary

As the water provider for the second largest city in the United States, the Los Angeles Department of Water and Power (LADWP) takes pride in ensuring our customers always have access to high quality, reliable and safe drinking water. This summary provides a snapshot of our efforts to meet all state and federal drinking water standards in 2025.

Securing our Water Future through Innovation and Sustainability

Around the globe, major population centers are grappling with water supply issues due in large part to climate change. For Los Angeles to thrive and stay “water-strong,” we need to reduce our reliance on imported water and prioritize the development and optimization of our local, in-basin water resources. One such project is already underway--the Los Angeles Groundwater Replenishment Program (LAGWR), which broke ground on December 6, 2024. As one of the largest potable reuse projects in California, LAGWR will create a drought-resistant local source of purified water, providing up to 45 million gallons daily to meet the drinking water needs of 500,000 customers, among many other benefits.

LAGWR will utilize the most advanced treatment technologies that exceed standing regulatory and health requirements. We are particularly excited about this project’s timing, as it will be operational just in time to showcase Los Angeles’ commitment to sustainability during the LA28 Olympics. Through continued investments in infrastructure modernization, water quality innovation, and strategic initiatives like LAGWR, we are building a foundation that will secure Los Angeles’ water resources for generations to come.

Celebrating 75 Years of Water Quality Excellence

This year, we celebrate a remarkable milestone of 75 years of continuous certification of the LADWP’s Water Quality Laboratory (WQ Lab) by the State of California. In September 1951, our laboratory became the first ever California state-certified drinking water laboratory. We have worked hard to build a legacy of scientific leadership and public health protection that continues to guide our work today.

Over the years, the LADWP WQ Lab has undergone significant technological advancements, and our monitoring programs handle a broader range of emerging contaminants. Our quality assurance systems continue to evolve to meet stringent accreditation standards, and we have also expanded our data management and reporting capabilities. Independent third-party audits consistently affirm our lab’s strong capabilities and quality management systems.

Innovation remains central to our operations as we continue to invest in advanced instrumentation and cutting-edge methods. As we look to the future, the LADWP WQ Lab is preparing to transition to a newer, state-of-the-art laboratory in 2030–31. These enhancements and facilities will ensure we continue to make decisions based on the best available science, so that our customers can remain confident in the safety of their drinking water.

Regulatory Compliance

In 2025, we tested for 240 constituents in the water and performed more than 100,500 tests on samples taken throughout our vast water system. LADWP met and complied with all the primary drinking water standards in 2025.

Reported Deficiencies and Corrective Actions

In January 2026, LADWP detected chlorate above the California notification level of 800 parts per billion (ppb) at the Cyprean Tank in Tujunga and the Highway Highlands Tank at Lookout Mountain. Once the elevated chlorate results were found, the tanks were drained and cleaned.

On May 31, 2023, the State Water Board identified a deficiency at Solano Reservoir stemming from small holes in its corrugated metal roof. A Corrective Action Plan was submitted for repair work with some of it completed August 4, 2023. Additional work is pending and LADWP is in continuous contact with the State Water Board to ensure full compliance.

On October 17, 2025, the State Water Board identified a deficiency at the Maclay Reservoir also due to holes and openings in its metal roof. A Corrective Action Plan was submitted, and the reservoir was drained—repairs will be completed and the reservoir put back into operation by end of summer 2026.

PFAS and Drinking Water in California

Poly- and Perfluoroalkyl Substances (PFAS) are a group of synthetic (man-made) chemicals that have been used in industry and consumer products since the 1940s. They break down very slowly in the environment, and most U.S. manufacturers voluntarily phased out production in the early 2000’s. LADWP has continued to monitor our groundwater sources for PFAS since we began testing in 2013; we have analyzed over 1,000 samples for PFAS utilizing testing methods by the U.S. Environmental Protection Agency (U.S. EPA).

Although PFAS were detected in a few samples from individual wells at the Pollock Well Field, ongoing testing of the supply confirmed that no PFAS compounds subject to proposed or actual State or Federal PFAS regulations were detected in water entering the distribution system

Lead and Copper Rule in Los Angeles

LADWP has a long and successful history safeguarding our customers from lead exposure. LADWP was one of the first utilities to incorporate the lead-free standard by initiating a program in 1998 to replace low-lead water meters with lead-free water meters. As of December 2025, more than 607,000 of the roughly 700,000 active water meters in LADWP’s water distribution system have been replaced. Based on the Lead and Copper Rule Revisions of October 2024, LADWP also completed an inventory of the service line materials, concluding there are no lead service lines present in the system. LADWP achieved a non-lead designation from the State Water Board.

Arsenic

Low amounts of arsenic were detected in drinking water in 2025, with the highest level detected at 7.0 µg/L.

While your drinking water meets the federal and state standard for arsenic, it does contain low levels of arsenic. The arsenic standard balances the current understanding of arsenic’s possible health effects against the costs of removing arsenic from drinking water. The U.S. EPA continues to research the health effects of low levels of arsenic, which is a mineral known to cause cancer in humans at high concentrations and is linked to other health effects such as skin damage and circulatory problems. 

Protecting Water Quality at the Source

Surface Supply

LADWP regularly monitors the Owens Valley and Mono Basin watersheds that supply the Los Angeles Aqueduct. This includes microbes such as Cryptosporidium and Giardia. Results indicate that their presence is extremely infrequent or at very low levels. The ultraviolet treatment provided at the Los Angeles Aqueduct Filtration Plant safeguards against Cryptosporidium and Giardia. Neither were found in treated water in 2025.

Groundwater Supply

Groundwater sources are located in highly urbanized areas. The wells within these aquifers are most vulnerable to the following activities: dry cleaning, manufacturing, metal finishing, septic systems, chemical processing, and storage of fertilizer, pesticides, and chemicals. LADWP has recently constructed major groundwater remediation facilities to ensure that the groundwater it serves is of the highest quality and meets all drinking water standards.

Purchased Imported Supplies from Metropolitan Water District

LADWP purchases water from the Metropolitan Water District (MWD) provided by the Colorado River Aqueduct and the State Water Project. Each source has different water quality challenges. Removal of specific contaminants can be more expensive than protecting water at the source. This is why MWD and other water agencies invest in improved watershed protection programs. Three of the five MWD treatment plants (F.E. Weymouth, Robert B. Diemer, and Joseph Jensen) supply water to the L.A. area. Results from MWD are provided to LADWP and are included in the report on Tables I, II, and III.