The drinking water provided to residents of Los Angeles is safe for consumption, consistently meeting or surpassing all federal and state public health standards set by the U.S. Environmental Protection Agency (EPA) and the California State Water Resources Control Board. The Los Angeles Department of Water and Power (LADWP) works continuously to ensure the quality of the water delivered to the tap. This high level of safety is achieved through a complex system of sourcing, advanced purification processes, and rigorous, ongoing quality monitoring. Understanding these steps provides the clarity necessary to confidently address questions about its safety.
Where Los Angeles Water Comes From
Los Angeles relies on a diverse network of sources to meet the needs of its over four million residents. The water supply is broadly categorized into local sources, including groundwater and water collected via the Los Angeles Aqueduct, and imported water. The Aqueduct brings surface runoff from the Eastern Sierra Nevada mountains.
Imported water, which often accounts for the majority of the supply, is purchased from the Metropolitan Water District of Southern California (MWD). This MWD water is drawn from two primary systems: the State Water Project, channeling water from Northern California, and the Colorado River Aqueduct. Local groundwater extracted from basins like the San Fernando Valley makes up the remainder, though its use is often limited by historical contamination requiring specialized treatment.
The Purification Process and Safety Compliance
The process of turning raw source water into safe drinking water involves multiple stages designed to remove contaminants and pathogenic microorganisms. Initial treatment involves coagulation and flocculation, where chemicals are added to make tiny particles clump together. These clusters are then removed through sedimentation and physical filtration, which clears the water of particulate matter and many pathogens.
Final disinfection is achieved primarily through the use of chloramine, a disinfectant composed of chlorine and ammonia. LADWP uses chloramine because it lasts longer in the distribution system and creates fewer disinfection byproducts than traditional chlorine. Advanced treatment technologies, such as ultraviolet (UV) disinfection plants, use high-intensity light to neutralize viruses and bacteria. The entire process is governed by the federal Safe Drinking Water Act and enforced by the California State Water Resources Control Board, which sets maximum contaminant levels (MCLs) that all treated water must meet.
Ensuring Ongoing Water Quality
Maintaining water quality requires continuous monitoring throughout the distribution network. The LADWP tests for more than 200 different contaminants and conducts tens of thousands of tests annually on samples taken from the source, treatment facilities, and points across the city. This extensive testing regimen checks for common concerns like bacteria, volatile organic compounds, and inorganic compounds.
The results of this monitoring are made publicly available each year in the Consumer Confidence Report (CCR), which serves as a transparent report card on compliance with all established drinking water standards. This report confirms that Los Angeles water consistently complies with all primary standards. The State Water Resources Control Board provides regulatory oversight, ensuring the utility is vigilant in its testing and reporting obligations.
Addressing Specific Consumer Concerns
While the municipal water supply meets safety standards, some consumer concerns relate to aesthetics and the condition of private plumbing.
Aesthetics and Hardness
The taste and odor of the water are the most frequent complaints, often resulting from the disinfectant chloramine. Los Angeles water is also considered hard due to high levels of naturally occurring minerals like calcium and magnesium. These minerals can lead to limescale buildup but pose no health risk.
Lead Exposure
A more significant safety concern involves lead exposure, which does not originate from the city’s main water supply, but rather from older plumbing inside private homes. Although LADWP service lines are lead-free, homes built before 1986 may still contain lead service lines, fixtures, or solder that can leach the metal into standing water. Residents in older homes, particularly those with vulnerable individuals like young children, can mitigate this risk by flushing their taps for a few minutes before use or installing point-of-use carbon filters certified to remove lead. These filters can also address taste and odor issues, providing an extra layer of reassurance for those with specific preferences or concerns about their household plumbing.