Baltimore’s municipal tap water consistently meets or exceeds federal health standards upon leaving the treatment plants. However, the quality can change significantly before it reaches a resident’s glass due to the challenges of a centuries-old public works system. The ultimate safety relies on rigorous regulatory oversight and the condition of the final delivery pipes leading into individual homes. Understanding the journey of the water is necessary for residents to make informed decisions about their consumption.
Where Baltimore’s Water Comes From
Baltimore’s water supply is sourced from surface water collected from multiple watersheds, primarily the Gunpowder Falls and the North Branch Patapsco River. This raw water is stored in three major reservoirs: Prettyboy, Loch Raven, and Liberty. These reservoirs collectively hold approximately 86 billion gallons of water, ensuring a reliable supply for the metropolitan area.
The water is transported through tunnels and mains to the city’s three filtration facilities: Montebello Plants I and II, and the Ashburton Filtration Plant. The Montebello plants (240 MGD combined capacity) are primarily supplied by the Loch Raven Reservoir. The Ashburton plant (165 MGD capacity) receives water from the Liberty Reservoir.
At these facilities, the raw water undergoes a multi-step treatment process to remove contaminants. This process includes chlorination to kill pathogens, and coagulation and flocculation, where chemicals like aluminum sulfate are added to clump fine particles together. The water is then filtered and disinfected before distribution.
Regulatory Standards and Testing
The quality of Baltimore’s public drinking water is governed by a stringent framework established by the federal government under the Safe Drinking Water Act. The U.S. Environmental Protection Agency (EPA) sets national standards, including Maximum Contaminant Levels (MCLs), which define the highest allowed concentrations of specific contaminants. The Maryland Department of the Environment (MDE) oversees the compliance of the Baltimore City Department of Public Works (DPW).
The city utilizes two MDE-certified laboratories, performing approximately 150,000 water quality analyses annually. This comprehensive testing ensures that the water meets all health-based limits before it enters the distribution system. Annually, the DPW publishes the EPA-required Consumer Confidence Report (CCR), detailing the water’s origin, treatment, and detected contaminant levels. This report is accessible online via the DPW’s website, providing transparency on system-wide compliance. Although the system generally meets compliance, the EPA has issued federal orders in the past, such as a 2023 citation for noncompliance regarding the covering or treatment of uncovered finished water reservoirs.
Localized Risks from Aging Infrastructure
The primary risk to tap water quality in Baltimore stems from the aging infrastructure that delivers the water from the treatment plants to individual properties. The distribution network contains many miles of older pipes, including lead service lines (LSLs) and galvanized pipes, which can introduce contaminants after the water has been treated. Lead, a powerful neurotoxin with no safe exposure level, can leach into the drinking water when these pipes corrode.
The DPW actively manages water chemistry by adding corrosion inhibitors to minimize this leaching. However, lead and copper can still be released from the service line—the pipe connecting the water main to the home—or from older household plumbing, fixtures, and solder. This means water quality at the tap can differ from the quality measured at the treatment plant.
In compliance with the EPA’s updated Lead and Copper Rule, Baltimore is undertaking an effort to identify and replace all LSLs. An initial inventory identified thousands of confirmed lead service lines and tens of thousands of lines with unknown materials. The city encourages residents to participate in a self-reporting survey to help identify their service line material composition.
Steps Residents Can Take to Ensure Safety
Given the localized risks from aging service lines and plumbing, residents can take several proactive steps to ensure the highest quality of water at their tap:
- Flushing the tap before use is a simple, effective measure, especially in older homes or after the water has been sitting in the pipes for several hours. Running the cold water for at least 30 seconds to two minutes clears any stagnant water in the service line or household plumbing, reducing potential lead and copper exposure.
- Installing a certified water filter provides a higher level of protection against contaminants that may enter the water after treatment. Residents should look for filters certified by the National Sanitation Foundation (NSF) to remove specific substances like lead (NSF/ANSI Standard 53 certification). Filters must be regularly maintained and cartridges replaced according to manufacturer directions.
Private Water Testing
For residents in older homes, particularly those built before 1986 or those with identified lead service lines, private water testing offers the most certainty about tap water quality. Home test kits are available to screen for contaminants like lead, but a certified laboratory test provides a more comprehensive and accurate analysis.
Using Cold Water
Using only cold water for drinking, cooking, and preparing baby formula is recommended. Hot water is more likely to cause lead to leach from plumbing fixtures.