Latest Testing Results

• Exceptional Water Quality: Memphis’s water consistently meets or exceeds all federal and state drinking water standards. MLGW’s Water Quality Assurance Laboratory conducts approximately 40,000 tests annually — far more than required — to ensure water quality. The Memphis Sand Aquifer’s natural purity means the water requires only minimal treatment before reaching taps.
• Lead Service Line Programme: MLGW stopped installing lead service lines in the 1950s, but an estimated 24,000 utility-side lead lines were originally installed in older areas of the city. Since 2012, MLGW has replaced or inspected over 9,000 lines. In 2024, MLGW submitted its full service line inventory to the EPA ahead of the October 2024 LCRR deadline. A full-line replacement pilot programme — covering both MLGW-side and customer-side lines, with replacement assistance available — launched in 2025, backed by $110 million committed over 10 years using federal infrastructure funds.
• EPA PFAS Compliance: Memphis Sand Aquifer water complies with the EPA’s 2024 PFAS maximum contaminant levels, including the 4 ppt limit for PFOA and PFOS. The Tennessee Department of Environment and Conservation (TDEC) is conducting ongoing statewide testing of all public drinking water sources for 29 PFAS compounds. The federal compliance deadline for all utilities is 2029.

Memphis Sand Aquifer Characteristics

• Ancient Water Source: The Memphis Sand Aquifer contains water estimated to be over 2,000 years old, having slowly filtered through multiple layers of sand and clay over millennia before reaching MLGW’s wells.
• Natural Protection: The aquifer is generally shielded by a clay confining layer that acts as a barrier against contaminants from the shallow aquifer above. Researchers at the University of Memphis’s Center for Applied Earth Science and Engineering Research (CAESER) continue to map areas where this clay layer is thin or absent — known as “breaches” — which require ongoing monitoring.
• Recharge Zones: The aquifer is primarily recharged in areas outside Shelby County where the protective clay layer is naturally absent, allowing rainfall to slowly replenish the groundwater supply over decades. See our Tennessee state water overview for broader context on statewide groundwater pressures.

Minimal Treatment Process

• Aeration: Due to the exceptional purity of Memphis aquifer water, treatment is minimal compared to surface water systems. The primary step involves aeration to remove naturally occurring iron and dissolved gases before distribution.
• Disinfection: The water is disinfected with sodium hypochlorite (a chlorine-based disinfectant) to ensure it remains free of harmful bacteria as it travels through the distribution system. This process produces disinfection byproducts — trihalomethanes at around 33 ppb, which exceed EWG health guidelines though remain below EPA’s 80 ppb legal limit. A certified activated carbon filter at the tap significantly reduces these byproducts.
• Additives: Small amounts of fluoride are added for dental health (at 0.7 mg/L), and sodium hexametaphosphate (a phosphate compound) is added as a corrosion inhibitor to coat pipes and reduce the risk of lead leaching from older plumbing materials.

Aquifer Protection Efforts

• Breach Monitoring: CAESER at the University of Memphis conducts ongoing studies to map and monitor potential breaches in the protective clay layer above the Memphis Sand Aquifer, informing MLGW’s operational decisions and wellfield management.
• Local Ordinances: In 2021, the Shelby County Commission and Memphis City Council passed ordinances to enhance aquifer protection from potential contamination sources, particularly near identified breach zones and wellfields.
• Cross Connection Control: MLGW maintains a Cross Connection Control Programme requiring appropriate backflow prevention devices to protect the water supply from contamination through plumbing system cross-connections. Check our boil water notices tracker for any active alerts in the Memphis area.

Future Challenges and Protections

While Memphis’s water is renowned for its quality, the city faces real challenges in protecting this precious resource long-term. Key concerns include the potential for contamination through identified breaches in the protective clay layer, industrial development near wellfields, and the presence of several Superfund sites in Shelby County where chemicals including arsenic, lead, chromium, and nickel have contaminated surrounding groundwater. Tennessee has also found PFAS contamination in 60% of rivers and lakes tested in Northeast Tennessee, and contaminated sewage sludge being applied to land statewide remains a concern for groundwater recharge zones. Community advocacy groups like Protect Our Aquifer work alongside MLGW, CAESER, and government agencies to promote sustainable water use, advance protective policies, and maintain public awareness about Memphis’s unique water resource. The 2026 focus on lead service line replacement — combined with PFAS compliance preparation and Superfund site monitoring — represents the core of MLGW’s water quality agenda for the coming years. Use our interactive water quality comparison tool to see how Memphis compares with other major US cities.