Tap water in Nashville is officially considered safe to drink and consistently meets or exceeds all federal and state standards. This safety applies to the water supplied by Metro Water Services (MWS) to customers in Davidson County and surrounding areas. MWS compliance ensures the water leaving their treatment facilities is of high quality. This article details the systems, processes, and homeowner actions that ensure the safety and quality of the water delivered to your tap.
Regulatory Framework and Water Source
Nashville’s drinking water primarily originates from the Cumberland River, with a smaller contribution from the J. Percy Priest Reservoir. Because this source water is susceptible to potential contamination, rigorous treatment and monitoring are necessary. Metro Water Services (MWS) is the local utility responsible for treating and distributing approximately 109 million gallons of water daily to over 220,000 accounts.
The regulatory foundation is the federal Safe Drinking Water Act (SDWA), which mandates standards set by the Environmental Protection Agency (EPA). The EPA establishes Maximum Contaminant Levels (MCLs) for over 90 regulated pollutants that public water systems must not exceed. Nashville’s MWS consistently reports zero violations of these regulations, demonstrating ongoing adherence to these limits.
MWS publishes an annual Consumer Confidence Report (CCR) that details the source water, testing results for regulated contaminants, and compliance with all standards. This report confirms the quality of the water supply and is readily available for review.
Nashville’s Water Treatment Process
Raw river water is transformed into drinking water at two primary facilities: the Omohundro and the K.R. Harrington Water Treatment Plants. The process begins with initial screening at the river intake to remove large debris.
The first stage is coagulation and flocculation, where chemicals like alum are added. This causes small, suspended particles (silt, mud, and algae) to stick together, forming larger, heavier clumps called “floc.” These clumps settle out in sedimentation basins, making the water clearer for the next step.
Next, the water undergoes filtration by passing through specialized media, typically layers of anthracite, sand, and gravel. This physical step removes remaining fine particles and ensures the water is clear before final disinfection. The filtered water is then stored in underground tanks called clear wells.
The final step is disinfection, which neutralizes any remaining bacteria or viruses. MWS creates its own chlorine bleach on-site using salt, water, and electricity. Additionally, MWS adds orthophosphate to the treated water as a corrosion control measure, coating the inside of pipes to prevent the leaching of metals into the supply.
Addressing Specific Concerns: Contaminants and Home Infrastructure
While the water leaving the MWS treatment plants is extensively tested and confirmed safe, concerns often arise from the plumbing infrastructure that carries the water to the tap. Contaminants like lead and copper are rarely present in the supply itself but can enter the water after it leaves the public mains. Lead primarily leaches into drinking water through contact with older lead service lines, lead-based solder used until 1986, or brass fixtures.
Lead and Private Plumbing
MWS is not responsible for the piping within private property, meaning homeowners in older buildings are susceptible to localized contamination. To minimize potential exposure, residents should flush their taps for 30 seconds to two minutes before using the water for drinking or cooking, especially first thing in the morning. This action clears out stagnant water in the home’s internal plumbing that may have picked up trace amounts of metals.
Aesthetic Concerns and Filtration
Aesthetic issues, such as taste, odor, and water hardness, are separate from safety hazards. Nashville’s water is characterized as moderately hard, containing higher levels of naturally occurring minerals like calcium and magnesium. These minerals are not a health risk but can cause scaling on fixtures and may affect the taste.
Disinfection byproducts (DBPs), such as Total Trihalomethanes (TTHMs), are sometimes detected and can contribute to a slight chemical odor or taste. DBPs form when the chlorine disinfectant interacts with organic matter in the source water. While MWS levels of DBPs are within the EPA’s legal limits, home filtration systems, particularly those with activated carbon, are effective at reducing both aesthetic issues and trace amounts of these byproducts.