The safety of Detroit’s tap water is a common concern, driven by increased media scrutiny of municipal systems nationwide. Current data indicates that the water delivered to the city meets or surpasses all federal and state standards established to protect public health. This article investigates the journey of Detroit’s water, from its source through the treatment process, and addresses the primary infrastructure risks that can affect water quality at the tap. We will also detail the specific steps consumers can take to ensure their water remains safe.
Understanding Detroit’s Water Source and Purification
The raw water supply for Detroit is sourced from the expansive Great Lakes system, drawing specifically from the Detroit River and Lake Huron. The system utilizes three main intake points—two in the Detroit River and one in Lake Huron—ensuring a diverse and resilient supply.
The Great Lakes Water Authority (GLWA) treats this raw water before it enters the Detroit Water and Sewerage Department (DWSD) distribution network. Treatment begins with a pre-treatment phase where chemicals are added to neutralize impurities, followed by physical screening to filter out larger debris.
The water then undergoes coagulation and flocculation, where chemicals cause microscopic particles to clump into heavier masses called “floc.” These clumps settle out in sedimentation basins, removing suspended solids. High-rate filtration is the next step, where the water passes through layers of sand and gravel to remove remaining fine particles.
Final disinfection uses chlorine or chloramine to eliminate pathogens like bacteria and viruses, ensuring the water is microbiologically safe. Some facilities also use ozone to enhance quality. This multi-barrier process is engineered to comply with all regulatory standards before the water is distributed to homes and businesses.
Official Compliance and Current Testing Results
Detroit’s drinking water quality is overseen by the U.S. Environmental Protection Agency (EPA) and the Michigan Department of Environment, Great Lakes, and Energy (EGLE). These agencies mandate continuous monitoring for hundreds of potential contaminants. Compliance standards are known as Maximum Contaminant Levels (MCLs), representing the highest concentration of a contaminant allowed in public drinking water.
The DWSD consistently publishes an Annual Water Quality Report (Consumer Confidence Report or CCR), detailing the results of this mandatory testing. This report confirms the system complies with all MCLs for contaminants, including bacteria, volatile organic compounds (VOCs), and disinfection byproducts (DBPs).
Levels of DBPs like Total Trihalomethanes (TTHMs) have been detected but remain below the regulatory MCL of 80 parts per billion. The system also adheres to the Michigan Lead and Copper Rule.
Lead testing, conducted at the tap in homes with known lead service lines, is summarized by the 90th percentile result. The 2024 testing showed the 90th percentile for lead at 13 parts per billion, which is below the state action level of 15 parts per billion.
Lead Service Lines: The Primary Risk at the Tap
While the treated water leaving GLWA facilities is lead-free, the primary risk for exposure occurs at the customer’s service line and indoor plumbing. A service line connects the water main to the home, and many older Detroit homes, especially those built before 1945, have lead lines. Corrosion in these pipes can cause lead particles to leach into the drinking water when it sits stagnant.
To mitigate leaching, the DWSD adds a corrosion inhibitor, typically phosphate, during treatment. This chemical forms a protective coating inside the pipes, preventing lead from dissolving into the water supply. This active corrosion control is a major factor in keeping the city’s lead test results below the action level.
The city is working to eliminate this risk through its Lead Service Line Replacement (LSLR) Program. The DWSD estimates 80,000 lead service lines need replacement. Michigan mandates replacement by 2040, but Detroit aims to complete the work within 10 years.
The replacement effort focuses on a neighborhood-by-neighborhood approach, prioritizing areas with older housing stock, high density of vulnerable populations, and low-income households. The program aims to replace 8,000 to 10,000 service lines annually, leveraging state and federal funding to ensure replacement is completed at no direct cost to the homeowner.
Steps Consumers Can Take for Added Safety
Detroit residents can take proactive steps to minimize exposure to potential contaminants, particularly lead, originating from home plumbing. Residents should first determine if their service line or interior pipes contain lead, which is most likely if the home was built before 1945. The DWSD provides resources to help residents identify their service line material.
If a lead service line is present, consumers should flush their taps before using water for drinking or cooking. Running the cold water for five minutes, especially after it has been sitting overnight, clears the water that has been in contact with the service line. Always use cold water for consumption, as hot water increases the rate at which lead and other metals dissolve from plumbing materials.
For added assurance, residents can request a free lead and copper testing kit from the DWSD to check water quality at their tap. This individualized testing is separate from the city’s mandatory compliance monitoring. Families with young children or pregnant women may choose to use a certified home water filter as a precautionary measure.
Point-of-use filters, such as pitcher or faucet-mounted devices, are effective and affordable options, but they must be certified by organizations like NSF International to remove lead. Whole-house filtration systems offer broader protection but require a higher investment. Proper maintenance and timely filter replacement are necessary to ensure any chosen device remains effective.