Nashville’s tap water is consistently regarded as safe to drink, meeting or exceeding all federal and state regulatory standards set by the Environmental Protection Agency (EPA) and the Tennessee Department of Environment and Conservation (TDEC). Metro Water Services (MWS) manages the water quality, treating and distributing water to customers in Davidson County and surrounding areas. Understanding the water’s source, treatment process, and potential post-treatment issues provides a fuller picture of its quality.
Where Nashville’s Water Comes From
The primary source for Nashville’s drinking water is the Cumberland River. MWS operates two major water treatment facilities, the Omohundro and K.R. Harrington Water Treatment Plants, which subject the raw river water to a multi-stage purification process to make it potable.
Purification begins with coagulation and flocculation, where chemicals are added to clump tiny particles together into larger masses called floc. The water then moves through sedimentation basins, allowing the floc to settle out by gravity. Remaining fine particles are removed during filtration. The final step is disinfection, typically using chlorine or chloramines to destroy harmful microorganisms before the water enters the distribution system. MWS also employs corrosion control additives to prevent materials from leaching out of pipes.
How Water Safety Is Monitored
The safety of Nashville’s water is governed by the federal Safe Drinking Water Act (SDWA), which mandates strict standards for over 90 contaminants. MWS complies with these standards, which are enforced locally by TDEC. The utility performs rigorous testing on water samples taken daily from the river, during treatment, and from the finished water supply.
MWS tests for over 100 substances, including regulated microbes and chemicals, and voluntarily monitors for unregulated contaminants like microplastics and Per- and Polyfluoroalkyl Substances (PFAS). The utility makes its water quality data transparent through the annual Consumer Confidence Report (CCR). This report details the source water, compliance status, and test results, confirming that MWS has consistently avoided drinking water violations.
Common Local Water Quality Questions
While the water leaving the treatment plants is safe, some water quality concerns may arise after the water enters private plumbing.
Lead Concerns
One primary concern is lead, which is not present in the treated water but can enter the drinking water from older service lines and household fixtures. MWS maintains a corrosion control program, feeding ortho-polyphosphate into the water to coat pipes and prevent lead from leaching out of materials, which has kept the 90th percentile lead level well below the EPA action level of 15 parts per billion. Residents in homes built before 1986 should be mindful of potential lead fixtures and should run cold water for a few minutes before drinking it, especially if the water has been sitting for several hours.
Hardness and Aesthetic Issues
Nashville’s water is also characterized as moderately hard due to naturally occurring mineral content, primarily calcium and magnesium. While hard water is not a health concern, the mineral content can lead to scale buildup on appliances and may affect the taste. Another aesthetic issue is the occasional chlorine taste or odor, which is a result of the disinfection process. The use of chlorine and chloramines can form disinfection byproducts (DBPs), but MWS maintains these levels within the federal regulatory limits.
Understanding Water Safety Advisories
Water safety advisories, such as a “Boil Water Notice,” are issued during non-routine events that could compromise the water supply. These advisories follow a major water main break, a loss of pressure in the distribution system, or a failed water sample test. A drop in pressure can create a risk for contamination by allowing outside water to enter the pipes.
If a boil water advisory is issued, residents must bring all water to a rolling boil for a minimum of three minutes and allow it to cool before use for drinking, cooking, brushing teeth, or making ice. Temporary discoloration, such as brown or cloudy water, can occur during hydrant flushing or maintenance. This discoloration does not usually require boiling, but MWS advises customers to report it and run the cold water until it clears. MWS uses its alert system and local news to quickly communicate safety advisories to the public.