Regulatory Compliance

LADWP works around the clock to ensure that the drinking water we deliver to our customers is of the highest quality and meets all safety requirements. Highly trained, certified treatment operators monitor our water treatment operations continuously, thereby helping meet federal and state standards for drinking water. In 2025, we tested for 240 constituents in the water and performed more than 100,500 tests on samples taken throughout our water system. LADWP complied with all the primary drinking water standards in 2025.

Chlorate

In January 2026, LADWP detected chlorate above the California notification level of 800 parts per billion (ppb) at the Cyprean Tank (located near Lookout Mountain) and Highway Highland Tank (located in Tujunga). A notification level is a health-based advisory level, but not an enforceable standard. These samples were collected by LADWP to assist with the implementation of new water quality treatment equipment (chloramination trailers) for storage tanks.

The Cyprean Tank was sampled and resampled in January 2026, with the highest reported value for chlorate at 3,390 ppb. Cyprean was not serving the system in January 2026; once the elevated chlorate results were reported, the tank was drained and cleaned. Cyprean functions primarily as backup storage and serves water into the distribution system when there is unusually high demand in the system. However, there were a few instances when some water from the tank entered the distribution system in the Lookout Mountain area between December 2024 and the end of 2025.

The Highway Highland Tank was sampled in January 2026 and the reported value for chlorate was 1,120 ppb. It was immediately taken out of service once the chlorate result was reported. The tank was then drained and cleaned, prior to being refilled. Between September 2025 and January 2026 water from the Highway Highlands Tank was served to the Tujunga area.

Chlorate can form as a byproduct when sodium hypochlorite chemical solution is stored at warm temperatures or for an extended period. LADWP is taking steps to prevent recurrence of elevated chlorate which include increased water quality testing and updating chemical storage procedures.

Short-term, low-level exposure to chlorate in drinking water, as in these instances, is generally not considered a significant health risk. Long term exposure at higher concentrations may lead to impacts on thyroid function or red blood cells.

Total Trihalomethanes in Griffith Park

Samples collected at Griffith Park in September 2023 contained levels of Total Trihalomethanes (TTHMs) exceeding the Maximum Contaminant Level of 80 parts per billion (ppb). The highest level found was 136 ppb. Compliance with the MCL for TTHMs is determined based on a running annual average calculated quarterly for each monitoring location. However, LADWP only has TTHM results in Griffith Park from this single September 2023 sampling event. TTHMs are byproducts of the disinfection process when chlorine is used and are typically more prevalent when temperatures are warm. Griffith Park is an isolated section of LADWP’s overall water distribution system that serves transient visitors and employees in Griffith Park but does not serve any residents.

Solano Reservoir Significant Deficiency

On May 31, 2023, the State Water Board identified a Significant Deficiency at Solano Reservoir. The deficiency is due to small holes in the corrugated metal roof of the Reservoir, where contaminants could potentially enter into the stored water supply. On June 27, 2023, LADWP submitted a Corrective Action Plan to the State Water Board which included patching accessible holes. This work was completed on August 4, 2023. However, some holes in the roof cannot be patched until the Reservoir is taken out of service and drained. To take the Reservoir out of service, a new trunk transmission line and pressure regulator station must be placed into service to provide water to the area currently served by Solano Reservoir. This new conveyance infrastructures is still under construction. In the interim, LADWP has been conducting weekly bacteriological sampling of this reservoir, and has been providing results to the State Water Board to demonstrate that the Reservoir continues to provide safe water to customers.

Maclay Reservoir Significant Deficiency

On October 17, 2025, the State Water Board identified a Significant Deficiency at Maclay Reservoir. This stems from holes and openings in the corrugated metal roof of the Reservoir where contaminants could potentially enter into the stored water supply. On November 14, 2025, LADWP submitted to the State Water Board a Corrective Action Plan to take the Reservoir out of service and conduct repairs to the roof. On February 10, 2026, LADWP removed Maclay Reservoir from service to drain it and repair the roof. The repairs are expected to be completed by July 2026.

Poly and Perfluoroalkyl Substances and Drinking Water in California

Poly- and Perfluoroalkyl Substances (PFAS) are a group of synthetic (man-made) chemicals which include Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS). This category of manufactured chemicals that have been used in industry and consumer products since the 1940s have characteristics that make them useful in a variety of products, including nonstick cookware, waterproof clothing, and firefighting foam, as well as in certain manufacturing processes. PFAS tend to break down very slowly in the environment. In the United States, PFOS was voluntarily phased out by its primary manufacturer between 2000 and 2002, and manufacture and import of PFOA were later phased out under EPA’s PFOA Stewardship Program.

Current scientific research indicates that exposure to certain PFAS may be associated with adverse health effects. Potential effects identified by EPA include reproductive effects, developmental effects in children, increased risk of some cancers, reduced immune response, and interference with the body’s natural hormones. More information is available on the U.S. EPA’s website: https://www.epa.gov/pfas/our-current-understanding-human-health-and-environmental-risks-pfas

On April 10, 2024, the U.S. EPA announced the final National Primary Drinking Water Regulation (NPDWR) for PFAS compounds, which included Maximum Contaminant Levels (MCLs) for PFOA (4 ng/L) and PFOS (4 ng/L). In 2025, the State of California established Notification Levels and Response Levels for PFOA (4 ng/L and 10 ng/L), PFOS (4 ng/L and 40 ng/L), Perfluorohexanesulfonic acid (PFHxS) (3 ng/L and 10 ng/L), and Perfluorohexanoic Acid (PFHxA) (1000 ng/L and 10,000 ng/L). California previously established Notification Levels and Response Levels for Perfluorobutanesulfonic acid (PFBS) (500 ng/L and 5000 ng/L).

The U.S. EPA also issued the fifth Unregulated Contaminant Monitoring Rule (UCMR5) to improve U.S. EPA’s understanding of the frequency that 29 PFAS are found in the nation’s drinking water systems. LADWP collected samples under UCMR5 in 2023 and 2024.

LADWP has continued to monitor its groundwater sources for PFAS since it began testing in 2013 and has analyzed over one thousand samples for PFAS utilizing EPA approved testing methods. Although PFAS were detected in a few samples from individual wells, no single well represents water provided to our customers. Water from individual wells is blended with water from other wells and is further diluted by blending with large volumes of surface water before entering the distribution system. LADWP has not detected any PFAS compounds regulated by the State of California, or the U.S. EPA, in samples taken at entry points to the distribution system. LADWP’s ongoing monitoring program and commitment to water quality and safety ensure that our water meets or exceeds all regulatory standards.

If you have questions, please contact our Water Quality Hotline at (213) 367-3182 or email us at waterqualityoffice@ladwp.com.

Lead and Copper Rule in Los Angeles

LADWP has a long and successful history safeguarding our customers from lead exposure in several ways. LADWP utilizes infrastructure pipes, meters, and materials that do not contain lead. Between 1978 and 2006, LADWP cleaned and cement-lined approximately 2,600 miles of unlined iron pipes (greater than four inches in diameter). In another proactive effort, LADWP’s staff located and removed approximately 12,000 known lead goosenecks from its water distribution system by 2005. LADWP was also one of the first utilities to incorporate the lead-free standard by initiating a program in 1998 to replace low-lead (8 percent lead) water meters with lead-free (0.25 percent lead) 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.

LADWP also ensures that the water served to our customers is non-corrosive. Corrosion is a natural process that occurs when materials undergo chemical reactions that result in their deterioration. The State Water Board evaluated LADWP’s corrosion control program and has deemed our system to be optimized for controlling corrosion.

Under the Lead and Copper Rule Revisions, LADWP also completed an inventory of the service line materials in the distribution system. In 2021, LADWP completed the utility-side inventory, and no lead service lines were found. In 2022, LADWP began assessing the customer-owned service lines for the presence of lead, and if detected, the lines would be replaced. The assessment was completed in October 2024 with the conclusion that no lead service lines are present in LADWP’s distribution system. LADWP has achieved a non-lead designation from the State Water Board. For more information on this, please visit LADWP’s water quality website. LADWP will continue to protect the public from exposure to lead by implementing the Lead and Copper Rule Improvements regulation that was finalized by the U.S. EPA on October 8, 2024.

LADWP regularly tests for lead and copper in our distribution system and in customer homes that have been identified as ideal for our residential testing efforts. As part of this continuing effort, LADWP conducted residential sampling for lead and copper in 2023 as part of the Lead and Copper Rule (LCR) tap water sampling program. This program focuses on single family residences built between 1982 to 1987 with original plumbing, which are expected to have copper pipes plumbed with lead solder. Customers with qualifying homes that participated in the sampling program had their tap water tested for lead and copper at no cost. During the 2023 sampling program, 105 first draw samples were obtained from customers’ homes and analyzed at LADWP’s Water Quality Laboratory. The results showed a 90th percentile of 3.9 ppb for lead and 529 ppb for copper. Both values were well below the respective Action Levels of 15 ppb for lead and 1,300 ppb for copper. The next LCR sampling round will be conducted in Summer of 2026.

Customers who think their home may qualify can participate in LADWP’s next round of LCR sampling between June and September 2026 by contacting the Water Quality Hotline at (213) 367-3182 or emailing us at waterqualityoffice@ladwp.com.

Lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. LADWP is responsible for providing high quality drinking water and removing lead pipes from its distribution system, but it cannot control the materials used in premise plumbing or fixtures. Therefore, it is important for customers and property owners to identify plumbing materials, and remove those with higher lead content. Use cold water for drinking and flush your tap for 1-2 minutes before drinking from it. You can do this in a water efficient manner by taking a shower, doing laundry, or a load of dishes. You can also use a certified National Sanitation Foundation-53 (NSF-53) filter to remove lead at the point of use. If you are concerned about lead in your water and wish to have your water tested, contact LADWP’s Water Quality Hotline at (213) 367-3182. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available at http://www.epa.gov/safewater/lead.

Fluoridation in Drinking Water

Our water system treats your water by adding fluoride to the naturally occurring level to help prevent dental cavities in consumers. State regulations require the fluoride levels in the treated water be maintained within a range of 0.6 to 1.2 mg/L with an optimum dose of 0.7 mg/L. Our monitoring showed that the fluoride levels in the treated water ranged from 0.2 to 0.8 mg/L with an average of 0.7 mg/L. Information about fluoridation, oral health, using low-fluoride water to prepare infant formula, and other current issues is available at: http://www.swrcb.ca.gov/drinking_water/certlic/drinkingwater/Fluoridation.shtml.

Arsenic

Low amounts of Arsenic were detected in your drinking water in 2025, with the highest level detected at 7.0 µg/L. Water systems with arsenic above 5 µg/L (50 percent of the MCL), but below or equal to 10 µg/L (the MCL) are required to provide you this information:

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.