The tap water supplied to the City of Raleigh is safe for consumption and complies with all federal and state drinking water quality regulations. Raleigh Water manages the entire system, from source reservoirs through advanced treatment facilities and into the distribution network. This utility serves over 650,000 residents across Raleigh and surrounding communities, including Garner, Wake Forest, and Knightdale. A comprehensive system of source protection, purification, and rigorous testing validates the water’s quality before it reaches residential taps.
Raleigh’s Water Sources and Supply System
Raleigh’s drinking water originates entirely from surface water sources, primarily two major reservoirs. The largest source is Falls Lake Reservoir, located north of the city in the Neuse River basin, which supplies the majority of the raw water. This water is directed to the E.M. Johnson Water Treatment Plant, the city’s largest facility.
The secondary source is Lake Benson, situated in Garner, which feeds the Dempsey E. Benton Water Treatment Plant. Utilizing two separate source waters and treatment plants provides operational redundancy and supply security for the service area. Raleigh Water manages approximately 2,500 miles of water distribution lines to deliver finished water to its customers.
The utility maintains a dedicated Watershed Protection Program focused on preserving the quality of raw water in the ecological areas surrounding the reservoirs. Protecting the source water minimizes contaminants entering the system, reducing the intensity of purification processes. Since surface water is susceptible to runoff, this upstream protection is a foundational component of the water quality strategy.
Treatment and Regulatory Compliance
Raleigh Water employs a multi-barrier treatment process at both plants to convert raw reservoir water into drinking water. The process begins with pre-treatment steps, such as adding ozone, a powerful oxidant that neutralizes organic compounds and taste-and-odor substances. Following this, chemicals like ferric sulfate are added to initiate coagulation, causing suspended solids and particles to clump together.
These larger clumps, known as floc, are separated from the water in a sedimentation stage using a solids contact clarifier. The clarified water proceeds to a multi-stage filtration system, which removes the remaining fine particles and microorganisms. This physical removal of particulates ensures the effectiveness of the final disinfection stage.
The final purification step involves a dual disinfection process using both ultraviolet (UV) light and chloramination (the addition of chloramines). UV light inactivates pathogens like Cryptosporidium and Giardia. Chloramination maintains a disinfectant residual throughout the 2,500 miles of the distribution system to prevent microbial regrowth. The entire process is mandated to meet the standards set forth by the Safe Drinking Water Act (SDWA).
Compliance is monitored through an aggressive testing schedule that extends beyond minimum federal requirements. Treatment plants regularly test the water for hundreds of potential contaminants to ensure maximum contaminant levels (MCLs) are not exceeded. Detailed compliance data is published annually in the Consumer Confidence Report (CCR), which is available to the public for full transparency on water quality status.
Specific Contaminant Concerns
A frequent concern is lead, which rarely originates in source water but enters drinking water through corrosion of household plumbing, such as lead service lines or older fixtures. Raleigh Water implements corrosion control measures to minimize the leaching of metals from pipes and has no known public lead service lines in its distribution system. Testing under the Lead and Copper Rule routinely shows lead levels significantly below the Environmental Protection Agency’s (EPA) action level of 15 parts per billion (ppb), often measuring less than 3 to 4 ppb.
The use of chloramines for disinfection can result in the formation of disinfection byproducts (DBPs), such as Total Trihalomethanes (TTHMs) and Haloacetic Acids (HAA5). These compounds are closely regulated, and Raleigh Water’s monitoring data shows DBP levels well below federal MCLs, validating the safety of the disinfection method. While chloramines may occasionally contribute to an altered taste or odor, the levels are safe and necessary for public health protection.
Emerging contaminants, including Per- and Polyfluoroalkyl Substances (PFAS), have been detected in the raw source water, prompting proactive measures. Raleigh Water has invested in advanced treatment technologies, such as powdered activated carbon (PAC) feed systems, to target and reduce these “forever chemicals.” These efforts aim to keep PFAS levels below the new advisory limits established by the EPA.
A common user concern is water hardness, which refers to the concentration of dissolved calcium and magnesium minerals. Raleigh’s water is generally classified as soft, with hardness levels ranging around 25 to 28 parts per million (ppm). This soft water characteristic means that in-home water softening systems are unnecessary for preventing scale buildup in appliances and plumbing.